I often use my thermal cookers to make soup - and usually the large volume being cooked means there isn't enough room to use the smaller pot for a separate item.
Today I made a simple beef stew - and remained very mindful of wanting to cook potatoes to serve with it. Even so there was only just enough space, about 7.5cm, for the top pot - so it was a bit gravied on it's base, when lifted out! (As thermal cookers work on retained heat, being full to capacity - and thoroughly heated - provides the best energy-bank).
I don't use a recipe for stew, so the ingredients vary according to what is in the fridge and cupboard! On this occasion I used:-
1 large onion, chopped
1kg gravy beef, cut into chunks
3 medium carrots, sliced
3 stalks celery, sliced
1/2 packet French onion soup powder
1 tin tomatoes, diced
1 tin brown lentils
1 cup frozen peas
1 cup frozen beans
2 cups beef stock (approx.)
1/2 cup red wine (approx.)
1/2 cup dried red lentils
Mixed herbs, salt and pepper to taste
I browned the onion and meat in a little olive oil, then added the other ingredients - in no particular order! There is no loss of liquid during thermal cooking so I include brown lentils break down to thicken the gravy. The mixture still looked a bit wet, so I also used some red lentils for extra thickening. (Dried mushrooms and vegetables are good for the same reason but generally I only have them if camping).
I left the mixture to come to the boil while I prepared the potatoes. Again, I filled the (smaller) pot as full as I could - and brought the potatoes to the boil. All up the larger pot probably simmered for at least 30-40 minutes while I was organising the potatoes (and other missions). The smaller pot simmered for a much shorter time.
Both pots were put into the outer thermal pot and locked down till dinner-time. Our stew was thick and steamy hot when we ate it, around 6-8 hours later. (There was plenty left to freeze as two further family-meal portions for later occasions).