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Wednesday, June 30, 2021

Hot Weather Cooking: Using a Thermos

So, back story a bit -- late last week, we could see that the coming Saturday, Sunday, and Monday were going to be terribly hot. And we don't have A/C or any other significant way to cool our meagerly insulated home, just a couple of table fans. So, every extra bit of heat added to our house on an already hot day makes us miserable. We decided that we wouldn't use the stove, oven, or even crockpot for the three hot days to come. This drove me to find alternative ways to cook. 

Obviously, the microwave is a great way to cook without heating the house. But I was also interested in finding other ways to cook. That's when I stumbled upon the idea of using a thermos to "cook" grains. I cooked both rice and oatmeal in a wide-mouth thermos.

To cook rice in a thermos, you need to parboil the rice and water for 5 minutes prior to putting it into a preheated thermos. (To preheat a thermos, boil a cup of water in the microwave and put into thermos then cap.) So, I used the microwave on reduced power (40%) for 5 minutes to cook the rice, water, and salt. After 5 minutes, I poured the preheating water out and rice, water, salt mixture into a thermos then allowed it to stand for an hour and a half. Afterward, I had cooked rice. I tried this with white rice, because it takes less time to cook in general. I haven't tried this with brown rice, but I did read that you can cook brown rice in a thermos this same way.

I also wanted to make some oatmeal to have for breakfast the next morning as we were low on other breakfast options. This time, I didn't bother preheating the thermos. For each serving, I boiled 2/3 cup of water in the microwave. I measured 1/3 cup of regular rolled oats and pinch of salt for each serving and put into the empty thermos, then poured the boiled water on top and sealed with the lid. I left this on the counter overnight and by morning, I had completely cooked oatmeal.

The "value" in using my thermos to cook grains was not just in keeping the kitchen cooler. But also, with the oatmeal in particular, my experiments showed me a way to "cook" food in a power outage or off the grid. I can usually find a way to boil water even without power, using Sterno, a grouping of candles under a pan (in a safe space, like inside my oven), the outdoor grill, or the evening fire pit while camping. 

Cooking the oatmeal in a thermos gave me an idea that I'll follow up on -- adding mix-ins to the oats and water the evening before. This could be a fun way for my family members to make their own customized oatmeal while camping or staying in a hotel. Everyone gets their own thermos and chooses from mix-ins like dried fruit, chocolate chips, chopped nuts/seeds, cinnamon, and brown sugar.


  1. I have never cooked anything in a thermos. I'm not sure we even have one, but it's an interesting idea.

    My son regularly does overnight oatmeal in the fridge. He puts all of the ingredients in a covered container and refrigerates overnight. No cooking. In the morning he has oats all ready to go. He eats them cold, but I guess you could do a quick zap in the microwave if you wanted them heated. I think you could do the same thing in a hotel room with an ice chest.

    1. I was also thinking about overnight oats as I read this! Great minds ....

      I remember reading about cooking hotdogs in a thermos with hot water--I think it was from the living on a dime blog, but I'm not sure about that. It was a way to feed a family if you had kids involved in outdoor sports--when families spend more time at the sports field than they do at home-- and I thought it seemed clever but being the klutz that I am, I was concerned that I would accidentally spill the hot water trying to get the hotdogs out and would burn myself.

      I have cooked couscous in the microwave before and I think you could possibly do that in a thermos.

      I didn't know what a Sterno was and had to Google it. :)

      Have you moved beyond the heat wave? We are supposed to get some rain today but I think we have moved beyond the massive amounts of rain we have seen over the past several days. Thank goodness.

    2. Hi Live and Learn,
      Great suggestion! I'm going to try overnight oats in the fridge and see if the texture works for me. Thanks for mentioning this. Every time I read that someone else does this it reminds me to try it.
      I eat leftover oatmeal cold all the time. Perhaps it's just the lazy in me. But I figure if cold oatmeal is fine by me, why waste time or energy to reheat it? The thermos oatmeal was just warm by morning and I didn't bother heating it to steaming hot.

      On a related note about food temperature tolerance and choices, I was drinking my coffee each morning cold. I mixed the instant granules into a mug of cold tap water and drank that. I didn't want the extra body heat generated by drinking a hot beverage. I found I was okay about the cold coffee. It wasn't an iced coffee drink with flavorings or sugar, but cold black coffee. However, although I was okay with it, I did feel that cold coffee wasn't as gastronomically interesting to me as hot coffee. So I drank far less of the cold stuff than I would have had it been hot.

    3. Hi Kris,
      I think you're right about couscous. I think that would work. Thank you! Also, this prompted me to check to see if quinoa would also work in a thermos. Evidently, someone has posted online about cooking quinoa in a thermos, too. So many new options!

      I've tried cooking hot dogs in a thermos. Here's my experience. We were on vacation in late winter (out sightseeing each day) and brought 2 thermoses with us. I filled them with hot water from the in-room coffee maker then put the hotdogs into the thermoses. (3 hotdogs fit in each thermos.) By lunchtime, the hotdogs were just warm. We ate them anyway in buns that I had brought with us for the day. They were just okay on a chilly day outdoors. I had hoped it would be a hot lunch for us. My thinking is the hotdogs had been in a fridge at 40 degrees, then put in hot water for several hours. The heat transfer between food and water would have meant the hotdogs didn't get piping hot. What would possibly work is to pre-heat the hotdogs, either in a microwave or in hot water, before putting into fresh hot water. I would need to experiment with this to see if the temp got high enough for food safety, if just using two successive batches of hot water. I think the microwave then hot water in thermos would be safe and would be a great way to have a "hot" lunch when out for a day in chilly weather.

      Thanks for asking. The heat wave broke yesterday with high temps about 88 or 89 F for the day. This morning, we have a marine layer cooling us off considerably. I hope that your excessive rain is now coming to an end and you have lovely summer days for the next couple of months!

    4. When my children were in school, I would heat up soup and also a hot dog separately. Then pour the soup in the thermos. Tie a string around the hot dog to make it easy for them to remove...then put itv down in the same thermos. I would pack a bun separately. This way they had a nice hot lunch. Not too relevant to hot weather...but just had to share a nice memory.

  2. In the summer I put a small table outside on my back deck and cook outside so that I don't heat up my house.I use my breadmachine,slow cooker,toaster oven,electric frying pan and a 2 burner hot plate as well as our b.b.q.

    1. Hi friend,
      I didn't think to get out the hot plate. I could use the crockpot and hot plate to cook on the deck. Thank you for your input. You've given me ideas for future heatwaves. It was so hot, we didn't want to even use the grill or do hot dogs over a fire. But I think using a few small appliances outdoors is a great idea!


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