A couple weeks ago, I finally bought a thermal cooking pot. It’s been on my radar for a long time, and I finally splurged. The basic idea is that it’s a pot-in-a-Thermos. You put your ingredients in the inner pot and bring it to a boil on the stove, then put that pot into the insulated outer pot, close the lid, and the food cooks using the retained heat. It’s sort of like a countertop version of haybox cooking, and the idea is to save energy and keep from heating up your kitchen when cooking.
I’ve learned that this gizmo has definite strong and weak points. I’m honestly not sure I’d recommend buying one; they are pretty pricey and it doesn’t do everything I’d hoped it would. Still, it works really well for some things, and I can’t stop experimenting! I thought I’d post the results of my experiments to date, so if you’re considering getting one, you can make a really informed decision. Details after the cut:
Beef stew. I browned a slice of beef shank and some meaty bones in the pot with a little oil and onion, then added water up to about 2″ below the top of the pot. (This is considerd “full.”) After it had boiled for 15 minutes, I put it into the outer pot and let it sit for 2 hours. Then I brought it back to a boil (which took only a minute or two) and put it back in the cooker for another hour. At that, point I had a really nice pot of beef stock. It was still steaming hot when I put it in the fridge overnight. The next day, pulled the meat off the bones and added carrots, onions, kale, barley, salt, and seasonings. Brought it to a boil and dropped it into the cooker for 30 minutes, and it was probably the best beef barley soup I’ve ever made. The carrots retained a nice “bite” and the barley was fully cooked. Usually, the carrots are overdone by the time the barley is cooked.
- Yogurt. This was the exception to the rolling-boil rule. Heated the milk to 180, cooled to 110, added diluted starter, and popped it in the pot overnight. In the morning, it was yogurt, with no attention, energy, or re-warming needed. I definitely prefer this over our previous cooler-with-hot-pack method.
- Coconut vegetable curry. Can of coconut milk, can of tomatoes, and a lot of chopped vegetables (including white and sweet potatoes). Bring to a boil, pop in pot for 30 minutes. Quite tasty; all veggies done nicely.
- Taking hot food to a potluck. It’ll keep food hot for several hours without added heat or electricity, so this is perfect for taking a pot of curry or chili to a potluck.
- UPDATE 10-31-09: Beans. I filled the pot a little over halfway with water and threw in a cup and a half of dried black-eyed peas. Soak overnight, bring to a boil, and throw in thermal sleeve for…a while. I had to go out, so mine were in there around 4 hours, and they were *perfect* when I got home. Cooked through, but not at all mushy. As an added bonus, black eyed peas do not make my heart race the way other beans do!
- UPDATE 11-3-09: Potatoes. Dice and cover with cold water (pot half full); bring to a boil and let sit in thermal sleeve for about 20-30 minutes.
- UPDATE 1-15-10: Making cheese. Bring up to temp over med-lo heat on stove, then pop into sleeve. Keeps it at a steady temp for at least 2 hours without having to fiddle with it or worry about burning.
- Chicken stock. Eventually, I did get good stock and tender chicken out of the pot, but it took several re-warmings and 4-5 hours of “steeping” time. I was also making stock out of the same batch of chickens on the stove, and to be fair, it took about 4 hours on a constant simmer. These were some tough old hens, and while the stock was great, the chicken never really got meltingly tender (even after pressure canning). I will continue to make stock in this pot when I’m doing one chicken at a time.
- Split pea soup. The batch was so small (1c peas and 3c water) that not enough heat was retained to cook them.
- Brown rice. I’ve tried this four times and ruined a really depressing amount of rice, both because of my own failure to measure ingredients, and the pot’s failure to cook.
- 2c rice, unknown water = fairly crunchy rice. Hmm, did I put in 2 or 4 cups of water? Well, I’ll just add some more hot water, like I do on the stove and I’ll end up with…wallpaper paste!
- 2c rice, 3c water = slightly crunchy rice. Um, Em? Do you remember that rice is supposed to be made with TWO cups of water for every cup of rice? No? Well, don’t you think it would be a good idea to MEASURE YOUR INGREDIENTS PROPERLY before blaming equipment failure? That’s a good girl.
- 2c rice, 4c water = fully cooked rice floating in a lot of hot water. You see, this pot doesn’t let steam out the way a pot on the stove does, which is why the 2c water/3c rice was only slightly crunchy. I just dumped this batch into a sieve and let it drain, and it actually was the best batch to date. Not perfect rice, but it was edible. Next time, I will try cooking 2c rice in 6 or 8c water and just plan to drain it like pasta.
- 1c rice, 2c water with complicated “double boiler” arrangement inside the pot = total failure. My idea was to put the rice and water inside a stainless steel bowl, and surround that with boiling water. I think the idea bears repeating, but by a different method – perhaps using a Mason jar on a silicone hot pad (so the jar doesn’t crack) with a lot more water around it so the inner pot can actually boil.
- 2 c rice, enough water to fill pot half full. Let it stand for one hour and it was completely overcooked.
- You must bring the contents of the inner pot to a full, rolling boil for a couple minutes before putting it into the thermal outer pot.
- The pot works best when it’s full (80% of 4.5 liters, in this case).
- It works poorly or not at all when it’s not full.
At one point, Thermos made a 6L version of this that came with two pots. You could either cook 2 different things at the same time, or fill one with water to help the other one cook. I can’t find it now, and I’m not sure if the difference between 3L and 4.5L would be enough to, say, get my rice to cook.
- See if I can find a way to do a pot-in-a-pot method that will let me cook smaller quantities of food.
- UPDATE: This hasn’t worked terribly well, though I did get a passable split pea soup by putting the soup ingredients in a small stainless steel pot and filling the thermal pot *around* it with water.
- Compare to a standard pressure cooker, which also uses less fuel than regular stove-top cooking, but does so at much higher heats. Supposedly it’s faster, too, but I’m not sure that it will be once you take cool-down/depressurizing time into account. But it might do a better job with rice and other things made in 1L instead of 4L quantities.