Mixed Mammal Stew: Beef, Lamb, and Pork in One Pressure Cooker
Some food names sound perfectly normal, and others make people stop and ask questions.
When I mentioned to a workmate that I was making a mixed mammal stew, the reaction was immediate. She was horrified. “Mixed mammal stew?” I thought she might ask if I had collected random creatures from a zoölogical garden and thrown them into a pressure cooker. That said, I have seen room-sized autoclaves used to sterilise large animals before exiting a high-containment facility.
The name sounds strange, but the reality is rather ordinary. After all, a mixed grill often contains beef steak, lamb chops, bacon, and eggs on the same plate. Sausages, meatloaf, and various European dishes regularly combine beef, lamb, and pork. Calling it “mixed mammal stew” highlights what is already there.
In this case, the stew combined chunks of beef chuck, lamb leg, and pork belly cooked under pressure with passata and some reserved cooking liquor from previous pressure-cooking sessions. Those earlier cooks included vegetables such as fennel, brown onion, and celery, so the cooking liquid carried their accumulated flavours. Although the vegetables had long since disappeared, their essence remained in the stock.
The result was a rich stew with tender pieces of three different meats. The beef contributed body, the lamb added its distinctive flavour, and the pork belly provided fat and gelatine.
Over several meals I served the stew in different ways. I paired one bowl with Hokkien noodles. I served other meals with rye sourdough toast, buttered twice in the style popularised by Nigella Lawson. The toast absorbed the cooking juices beautifully, making for a satisfying accompaniment.
Here are a few ways I ate the mixed mammal stew.
Mixed Mammal Stew Recipe
Serves
6 to 8 portions
Equipment
Pressure cooker
Chopping board
Sharp knife
Measuring jug
Wooden spoon spatula
Serving bowls or plates
Ingredients
For the stew
500 g beef chuck, cut into large cubes
500 g lamb leg, cut into large cubes
500 g pork belly, cut into chunks
500 mL passata
500 to 750 mL reserved pressure-cooker cooking liquor or stock
1 teaspoon sea salt
1 teaspoon freshly cracked black pepper
For serving
Option 1
Cooked Hokkien noodles
Finely chopped chives
Freshly cracked black pepper
Butter
Option 2
Rye sourdough bread
Butter for double-buttering
Finely chopped chives
Freshly cracked black pepper
Instructions
Place the beef chuck, lamb leg, and pork belly into the pressure cooker.
Pour in the passata and cooking liquor.
Season with salt and pepper.
Stir gently to combine.
Secure the lid and cook on high pressure for 45 minutes.
Allow the pressure to release naturally for 15 to 20 minutes before venting any remaining pressure.
Open the lid and stir the stew.
If the liquid is thinner than desired, simmer with the lid off until reduced to your preferred consistency.
To serve with Hokkien noodles
Cook the noodles according to the packet instructions.
Divide the noodles between bowls.
Ladle the mixed mammal stew over the noodles.
Add a knob of butter.
Finish with chopped chives and freshly cracked black pepper.
To serve with double-buttered rye sourdough toast
Toast thick slices of rye sourdough.
Butter the toast while hot.
Allow the butter to melt into the bread.
Spread a second layer of butter on top.
Serve alongside the stew with chopped chives and black pepper.
Thoughts
This stew began as a practical exercise in using what was available. It used beef chuck, lamb leg, and pork belly that needed cooking, plus some valuable cooking liquor left over from previous pressure-cooker sessions.
One advantage of keeping flavourful cooking liquid is that each batch contributes to the next. Fennel, onion, celery, and tomato notes gradually accumulate and create a deeper base than plain stock or water.
The stew may have an unusual name, but it’s conceptually no different from many dishes that combine multiple meats. Calling it mixed mammal stew makes the biology more obvious.
Whether served with noodles or thick slices of double-buttered rye sourdough, it was an enjoyable way to stretch one batch of pressure-cooked meat across several meals.
A pressure-cooked pulled pork and pancetta croissant sandwich
Sometimes a recipe starts with a plan, and sometimes it starts with a search. This one began as a rummage through the refrigerator and a desire to turn a rack of pork ribs into something I could enjoy in a sandwich.
This recipe combines pork ribs, pancetta, passata, fennel, onion, and celery in a pressure cooker to produce pulled pork. The vegetables melt into the sauce, the pancetta contributes salt and porky depth, and the passata provides sweetness and acidity. The result is spoon-tender meat that shreds itself.
Pile the pulled pork into a warm, buttery croissant, and you have a thoroughly indulgent sandwich.
A brief history of the pulled pork sandwich
Pulled pork is most closely associated with the barbecue traditions of the American South. Historically, whole pigs were cooked slowly over wood fires for many hours. Once cooked, the meat was chopped or pulled apart and served with regional sauces.
The pulled pork sandwich evolved as a practical way to serve this meat. Soft bread rolls made the barbecue easier to eat.
While traditional barbecue relies on low-and-slow smoking, modern cooks can achieve remarkably similar tenderness using a pressure cooker. The pressure cooker dramatically shortens the cooking time while preserving moisture and concentrating flavour.
This recipe is not intended to replicate authentic Southern barbecue. Instead, it borrows the idea of tender, shredded pork and reimagines it with a flaky croissant.
Serves
4 generous sandwiches or one for Gary
Ingredients
For the pulled pork
1 rack pork ribs, approximately 1.2 to 1.5 kg
200 g pancetta, diced
1 brown onion, finely diced
1 fennel bulb, finely diced
2 celery stalks, finely diced
20 mL apple cider vinegar
500 mL passata
250 mL water
2 teaspoons sea salt
1 teaspoon freshly ground black pepper
For serving
4 large freshly baked croissants or one plus lots of leftover meat
Equipment
Pressure cooker capable of reaching high pressure (approximately 12 psi or 80 kPa above atmospheric pressure)
Sharp knife
Chopping board
Measuring spoons
Tongs
Large bowl
Forks for shredding
Fine-mesh strainer (optional)
Method
Prepare the ingredients
Remove any loose membrane from the pork ribs.
Dice the pancetta.
Roughly cut the onion, fennel, and celery.
Pressure cook
Add the pancetta.
Add the onion, fennel, and celery.
Add the passata and water.
Nestle the pork ribs into the sauce.
Secure the lid.
Cook at high pressure (80 kPa above atmospheric pressure or approximately 12 psi) for:
45 minutes for smaller racks
50 minutes for larger racks
Allow a natural pressure release.
Shred the pork
Remove the ribs and place them in a large bowl.
Allow them to cool for 5 minutes.
Pull the meat from the bones using forks or gloved hands.
Discard the bones and any large pieces of cartilage.
Finish the sauce
Simmer the cooking liquid for 10 to 15 minutes until slightly thickened.
Return the shredded pork to the pressure cooker.
Stir thoroughly so the meat absorbs the sauce.
The finished pork should be moist, rich, and easy to spoon onto a sandwich.
Assemble the croissant sandwich
Slice each croissant horizontally.
Lightly toast if desired.
Fill generously with the pulled pork mixture.
Spoon over a little extra sauce.
Garnish with chives.
Serve immediately while the croissant remains crisp and flaky.
Serving suggestions
This sandwich is rich, buttery, and intensely savoury. It pairs best with sides that provide freshness and texture.
Consider serving with:
A shaved fennel and celery salad dressed with lemon juice.
Crisp coleslaw.
Pickled red onions.
Cucumber ribbons.
Roasted sweet potato wedges.
A simple green salad with rocket and parmesan.
For a brunch presentation, serve the croissant alongside a small salad of fennel, parsley, and celery leaves.
For a more substantial meal, serve with roasted vegetables and extra passata on the side.
Notes for success
Pork ribs contain enough connective tissue to create a luscious pulled-pork texture when pressure-cooked.
Natural pressure release is important. Rapid release may cause the meat fibres to tighten.
Pancetta contributes both seasoning and body to the sauce. Taste before adding extra salt.
A buttery croissant creates a luxurious contrast to the rich tomato-braised pork.
Leftover pulled pork will keep in the refrigerator for up to 3 days and reheats beautifully in a saucepan over low heat.
Final thoughts
Pull Pork Sandwich is what happens when you rummage around the refrigerator, find some pork, and then go and buy a croissant. The pressure cooker transforms pork ribs into tender strands of flavour-packed meat, while fennel, pancetta, and passata create a savoury sauce. Stuffed inside a flaky croissant, it becomes messy, indulgent, and entirely worth the extra napkins. It may not be traditional pulled pork, but it is delicious for anyone.
2 racks pork ribs (approximately 1.5 to 2 kg total)
1 teaspoon sea salt
1 teaspoon freshly cracked black pepper
2 teaspoons dried fennel seeds
For the braising base
1 brown onion, roughly sliced
1 fennel bulb, sliced into wedges
2 celery stalks, sliced
500 mL passata
250 mL water
1 teaspoon sea salt
½ teaspoon black pepper
1 teaspoon dried fennel seeds
Equipment
Electric pressure cooker or stovetop pressure cooker
Sharp knife
Chopping board
Measuring spoons
Tongs
Large serving platter
Small bowl for resting the cooked ribs
Instructions
1. Prepare the ribs
Remove the membrane from the back of the ribs if it is still attached.
Season both sides generously with:
1 teaspoon salt
1 teaspoon black pepper
2 teaspoons fennel seeds
Allow the ribs to sit while preparing the vegetables.
2. Prepare the cooking base
Place the following into the pressure cooker:
Sliced onion
Fennel wedges
Celery
Passata
Water
Remaining salt
Remaining pepper
Remaining fennel seeds
Stir gently.
The vegetables will form a trivet-like base that keeps the ribs slightly elevated above the liquid.
3. Load the cooker
Cut the racks into manageable sections if necessary.
Arrange the ribs vertically or lean them against the sides of the cooker, nestling them among the vegetables.
Avoid packing them too tightly.
4. Pressure cook
Seal the cooker and cook at high pressure for:
35 minutes
Allow a 15-minute natural pressure release before manually releasing any remaining pressure.
5. Finish the sauce
Carefully remove the ribs and set aside.
Using a spoon, stir the vegetables into the sauce. The pressure cooking process will have softened the onion, fennel, and celery until they are almost melting.
If the sauce is thinner than you like, simmer it uncovered for 5 to 10 minutes using the sauté function until slightly reduced.
6. Serve
Arrange the ribs on a platter.
Spoon the fennel and tomato sauce generously over the ribs.
Finish with additional cracked black pepper.
Notes from Yummy Lummy
The beauty of this dish is the fennel. Many people think fennel belongs only in salads or with fish. That’s a mistake. Fennel and pork are old friends. The sweet aniseed flavour balances the richness of the pork and softens beautifully under pressure.
The passata contributes acidity and sweetness without the fuss of peeling and crushing tomatoes. After 35 minutes under pressure, the vegetables collapse into a thick rustic sauce that tastes as though you’ve spent an afternoon tending a stove instead of pressing a button and waiting.
Educational Information: Pork Ribs
What are pork ribs?
Pork ribs are cut from the rib cage of the pig and contain a mixture of:
Bone
Connective tissue
Fat
Muscle
The connective tissue is rich in collagen.
Why pressure cooking works so well
Collagen is tough when undercooked. Given enough heat and moisture it converts to gelatin. Gelatin gives ribs their:
Succulent texture
Sticky mouthfeel
Rich flavour
Pressure cooking accelerates this process because water boils at a higher temperature under pressure than it does in a conventional pot.
Spare ribs versus baby back ribs
Baby back ribs
Shorter and more curved
Leaner
Slightly more tender
Spare ribs
Larger and flatter
More fat and connective tissue
Richer flavour
Both work well in a pressure cooker, although spare ribs particularly benefit from the extended moist heat.
Food safety
For pork, modern food safety guidelines focus on achieving a safe internal temperature rather than overcooking. Ribs destined for tenderness are usually cooked well beyond the minimum safe temperature because collagen breakdown requires higher temperatures and longer cooking times.
Grilled pork chops with pressure-cooker-stewed fennel and Granny Smith apple
A simple Yummy Lummy-inspired meal: pig, anise-sweet fennel, sharp green apple, heat, pressure, and appetite.
Introduction
This is dinner for when you want something meaty, sharp, sweet, and soft without making a fuss. The pork chops are grilled hot and rested properly. The fennel and Granny Smith apple are cooked under pressure until they collapse into a silky, savoury-sweet stew. Pork and fennel are a classic pairing because pork brings richness and fennel brings a gentle anise sweetness. Apple joins the party with acid and freshness, especially when it is a tart Granny Smith. I do like tartness.
Serves and timing
Serves: 2 Gary-type people or 4 normal people. I’m having the second serve tomorrow night.
Preparation time: 15 minutes.
Pressure cooking time: 3 minutes at high pressure, plus 5 minutes natural release.
Grilling time: 8 to 12 minutes, depending on chop thickness.
Resting time: 5 minutes.
Ingredients
For the pork chops
2 bone-in pork chops, about 250 to 300 g each and 2.5 cm thick.
1 teaspoon coarse cooking salt.
½ teaspoon freshly ground black pepper.
For the pressure cooker stewed fennel and Granny Smith apple
1 large fennel bulb, trimmed, fronds reserved, bulb cut into 1 cm wedges.
2 Granny Smith apples, unpeeled; keep the core and seeds, and cut into wedges.
1 small brown onion, peeled and quartered.
1 tablespoon beef fat.
½ teaspoon coarse cooking salt.
¼ teaspoon freshly ground black pepper.
125 mL mixed mammal cooking liquor.
1 tablespoon apple cider vinegar.
1 teaspoon Dijon mustard.
Method
1. Season the pork
Pat the pork chops dry with kitchen paper.
Season both sides and the fatty edge of each chop.
2. Pressure cook the fennel and Granny Smith apple
Set the pressure cooker to sauté mode.
Add the beef fat and let it melt.
Add the onion, fennel, salt, and pepper.
Cook for 3 minutes, stirring often, until the onion softens and the fennel smells sweet.
Add the Granny Smith apple wedges, cooking liquor, apple cider vinegar, and Dijon mustard.
Stir once, scraping the base so nothing is stuck.
Seal the pressure cooker and cook on high pressure for 3 minutes.
Allow a 5 minute natural release, then carefully vent the remaining pressure.
Open the lid, stir gently, and simmer on sauté mode for 2 to 4 minutes if you want a thicker stew.
Taste and adjust with a little more salt, pepper, or vinegar if needed.
3. Grill the pork chops
Heat a grill plate, barbecue, or heavy pan until hot.
Place the chops on the grill and cook for 4 to 5 minutes on the first side.
Turn and cook for another 4 to 5 minutes on the second side.
Stand the chops on the fatty edge for 30 to 60 seconds to render and crisp the fat.
Check the internal temperature. Aim for 63 °C in the thickest part, then rest the chops. The temperature will rise slightly as they rest.
Rest the chops on a warm plate for 5 minutes before serving.
4. Serve
Warm dinner plates before serving. A warm dinner plate can have a remarkable effect on the enjoyment of a meal.
Spoon the stewed fennel and apple onto warm plates.
Place a rested pork chop on top, or beside the stewed fennel and apple.
Add a final crack of black pepper.
Garnish with fennel fronds and pickled pomegranate arils.
Eat while hot, preferably with no apology for enjoying the fat.
Homer Simpson’s pork chop moment
There is something wonderfully uncomplicated about a pork chop. Homer Simpson would understand this meal. I can imagine him at the table, fork in hand, eyes fixed on the chop, giving the sort of pleased murmur usually reserved for doughnuts. The fennel and apple would probably be described as “the fancy green and white stuff”, but once the pork juices run into it, even Homer would know it belongs on the plate.
Adelaide Central Market wander
Before cooking this pork chop dinner, I had one of those Adelaide Central Market visits that makes a person glad to live near good food. I wandered through the Market and stopped at Skala Artisan Bakers, a South Australian bakery known for bread, pastries, and cakes, and bought a couple of potato pies. There is something deeply reassuring about a pie with potato on top. It is practical. It is filling. It is not trying to be delicate.
I also picked up a couple of Portuguese tarts from Saudade, the Adelaide Central Market stall specialising in pastel de nata. These little custard tarts are a joy. The pastry should be crisp and flaky, with enough structure to hold the custard, yet tender enough to shatter slightly when bitten. The custard should be smooth, sweet, and gently eggy, with a burnished top that says heat has done its good work. These also had powdered cinnamon on top, which added a warm, sweet spice note without overpowering the custard. I like them still slightly warm if possible, but I am not proud; room temperature is also fine when the tart is good. Potato pie first, Portuguese tart later, and pork chops for dinner. That is a nice little food day.
Cooking notes
Do not overcook the pork. A meat thermometer is the most reliable way to keep pork juicy.
Cut the fennel thicker if you want more texture. Cut it thinner if you want it to melt into the apple.
Granny Smith apples are useful here because their sharpness balances the pork fat.
If the stew tastes flat, add a splash more apple cider vinegar.
If the stew tastes too sharp, stir in a small knob of butter.
I exploited Microsoft Copilot to refine and format this blog post. Artificial intelligence large language models can make mistakes.
I exploited ChatGPT to add the cartoon bubble to the photograph of me. I also exploited ChatGPT to whiten my teeth. You do not need to see how yellow they are after all the coffee that I drink.
This meal brings together a smoked pork hock, fennel bulb, brown onion, salt, and mixed mammal liquor in the pressure cooker. It is simple food with an appetite behind it: smoky pork, sweet anise-like fennel, savoury onion, and a rich cooking liquor that becomes more than the sum of its parts.
Jump to the recipe.
Why pork and fennel work so well.
Pork and fennel are a classic pairing because they balance each other. Pork hock is rich, smoky, salty, gelatinous, and deeply savoury. Fennel brings sweetness, freshness, and a gentle anise flavour. When cooked under pressure, the fennel collapses into the liquor, softening the heaviness of the meat while also perfuming the dish.
This is the same sort of logic behind pork and apple, beef and onion, lamb and rosemary, chicken and leek, or fish and lemon. Meat gives fat, protein, and depth. Vegetables, herbs, and fruit bring water, acid, sweetness, bitterness, or aroma. Good combinations keep the mouth interested.
About pork hocks
A pork hock is the lower part of the pig’s leg, close to the ankle joint. It contains bone, skin, connective tissue, fat, and hard-working muscle. That means it can be tough if rushed, but it becomes tender and succulent when cooked long enough for the collagen to soften into gelatine. A smoked pork hock adds another layer: salt, smoke, and cured-pork flavour.
I have written before about pork hock and pork knuckle on Yummy Lummy. The Hahndorf Inn pork hock was a generous Bavarian-style meal with crunchy crackling, sauerkraut, mashed potato, mustard, and gravy. I also mentioned pork knuckle in a Queensland Day post, where the knuckle was cooked slowly, chilled, and then finished in an air fryer. See Crispy skin pork hock at the Hahndorf Inn and Queensland Day.
About fennel
Fennel bulb is crisp when raw, with a fresh anise aroma. Once cooked, it softens and becomes sweet, mild, and silky. In this dish, fennel works as both a vegetable and an aromatic. It does not dominate the pork; it lifts it.
Fennel also suits pressure cooking. The bulb breaks down enough to flavour the liquor, while some pieces remain recognisable if cut thickly. The result is a sauce-like vegetable base rather than a separate side dish.
Ingredients
1 smoked pork hock
1 fennel bulb trimmed and quartered.
1 brown onion, peeled and quartered.
Salt, used carefully because the pork hock is already smoked and cured.
Mixed mammal liquor, enough to cover the base of the pressure cooker.
Greek-style yoghurt, to serve.
Pickled pomegranate arils, to serve.
Polish sauerkraut, to serve.
Method
Place the quartered fennel and brown onion in the base of the pressure cooker.
Sit the smoked pork hock on top of the vegetables.
Add the mixed mammal liquor. Do not overfill the cooker.
Add only a little salt, if needed.
Seal the pressure cooker and cook on high pressure for 40 minutes.
Allow the cooker to vent naturally. This matters because a natural release helps the meat stay succulent and reduces the risk of drying the hock.
Open the cooker carefully, remove the pork hock, and let it rest briefly.
Pull the meat from the bone or serve the hock whole, depending on appetite and presentation.
Spoon over some of the fennel, onion, and cooking liquor.
Serving
Serve the pork and fennel with Greek-style yoghurt, pickled pomegranate arils, and Polish sauerkraut. The yoghurt cools the meat. The pomegranate arils add vivid tartness and colour. The sauerkraut brings crunch, acidity, and a pleasing fermented edge.
This is a meal for eating with a spoon and fork.
Cook’s notes
Smoked pork hock can be salty, so season cautiously.
Natural pressure release is worth the wait because the meat remains moist and relaxed.
If the liquor tastes too salty, dilute it with water or unsalted stock before serving.
Leftover pork can be folded through sauerkraut, added to soup, or eaten cold with yoghurt and pickles.
Final thoughts
Pork and fennel is a combination that makes sense. The hock gives smoke, salt, fat, and gelatin. The fennel provides sweetness and fragrance. The onion rounds everything out. The yoghurt, pomegranate, and sauerkraut make the plate lively rather than heavy.
References and notes
Yummy Lummy. 2026. “Crispy skin pork hock at the Hahndorf Inn.” Notes: describes a Bavarian-style pork hock meal with sauerkraut, mustard, mashed potato, gravy, tender meat, and crisp crackling.
Yummy Lummy. 2026. “Queensland Day.” Notes: includes pork knuckle served with sauerkraut and peas, finished in an air fryer after slow cooking and chilling.
Pressure cooking note. A high-pressure cook followed by natural release is commonly used for collagen-rich pork hock because it helps produce tender, gelatinous meat.
Microsoft Copilot was exploited to assist in creating this blog post.
TyreFix
I woke up this morning and started going for a drive. Discovered that there was low tyre pressure in one of my tyres. Fortunately, there was a servo nearby, so I was able to re-inflate the tyre. I went online to find a tyre repair service open on a Saturday morning. TyreFix came up as a 24-hour-a-day, seven-day-a-week service at very affordable prices. The best thing about TyreFix is that they come to you. It’s a mobile service. I called the mobile telephone number and provided my address and tyre details. The owner arrived at my place within 30 minutes. He repaired the tyre within 15 minutes. I was able to pay with a credit card on the spot. After the repair, there is a three-month warranty. This is a fantastic service. The person who answered the telephone was very friendly and very helpful. The person who came out, the company owner, was a delightful gentleman. He was very informative and very helpful. I highly recommend TyreFix.
Can a Humidifier Change the Way a Gas Stove Burns?
I started using a new humidifier this week. Within a day, I noticed the flames on my gas stove top were yellow rather than blue. I was worried about a supply problem, which could mean a carbon monoxide danger. I was prepared to contact a plumber but thought I would search for answers on the likely causes of yellow gas stove flames. I wanted to know about the temporal relationship between using a humidifier and the change in gas flame colour.
A portable humidifier seems like a simple household appliance: it adds moisture to dry indoor air. But when a humidifier is operated in a home—particularly in a closed room—it raises an interesting question: can increasing indoor humidity change the combustion of a gas stovetop burner?
Ultrasonic and cool-mist humidifiers are commonly used to increase indoor humidity. However, unlike evaporative humidifiers, they can do more than add moisture to the air: they can aerosolise minerals dissolved in the water.
This raises an interesting question for homes with gas cooking: can these mineral aerosols enter a gas-stove flame and alter combustion?
It’s more than just water vapour
An ultrasonic humidifier uses high-frequency vibrations to produce microscopic water droplets. As these droplets evaporate, dissolved minerals remain suspended as airborne particles. Depending on the water source, these can include calcium, magnesium, sodium, and potassium.
This phenomenon is responsible for the familiar “white dust” that can accumulate around ultrasonic humidifiers. Experimental studies have demonstrated that ultrasonic humidifiers can substantially increase airborne concentrations of minerals when operated with mineral-rich tap water.
Low-mineral or distilled water should be used in ultrasonic humidifiers when possible, and the reservoir should be cleaned regularly.
What happens when mineral aerosol reaches a gas flame?
A natural-gas cooktop burns predominantly methane:
CH₄ + 2O₂ → CO₂ + 2H₂O + heat
The flame operates at temperatures high enough to transform mineral particles entering the combustion zone.
Of particular interest are sodium and potassium, both alkali metals. Sodium and potassium originating from particles can enter methane flames and produce characteristic optical emissions. This is the same basic phenomenon responsible for the familiar yellow colour of a sodium flame.
Alkali-metal compounds can also interact with combustion chemistry. Potassium-containing compounds can influence methane and LPG flames, including inhibiting flame reactions at sufficiently high concentrations.
But does a household humidifier significantly change gas combustion?
While a visible yellow or orange gas flame should not automatically be attributed to a humidifier, burner contamination, blocked ports, incorrect gas pressure, inadequate primary-air mixing, or burner-cap misalignment are much more likely explanations and should be investigated.
However, when I stopped using the humidifier, opened all the doors and windows, and flushed my home with fresh air, the gas stove-top burners burned blue rather than yellow.
Humidity and mineral aerosol are different issues
It is important to distinguish two potential effects.
Water vapour can influence combustion at sufficiently high concentrations by diluting the combustion gases and altering flame temperature and reaction kinetics.
Mineral aerosol, however, introduces actual chemical elements and compounds into the combustion zone. Sodium, potassium, and other minerals can undergo high-temperature transformations and interact with flame chemistry.
Therefore, the potential association is not simply:
ultrasonic humidifier → aerosolised mineral-containing droplets → airborne mineral particles → possible transport into gas flame → potential interaction with combustion chemistry
The bottom line
There is a genuine scientific association between ultrasonic humidifiers, aerosolised minerals and gas-flame chemistry. Mineral-containing particles can be generated by ultrasonic humidifiers, and sodium- and potassium-containing material can interact with methane flames.
The prudent approach is therefore simple: control humidity, minimise mineral aerosolisation, maintain the humidifier properly, and ensure that gas cooking is adequately ventilated.
