Thermos Cooking

I live in a warm climate & air conditioning can be expensive, so I minimize inside heating during the summer.  So ... when I have to cook something, it's nice to only have to fire up whatever cooker I'm using once and for a short time ... and create several meals at the same time. 

Some of you may not have heard of Thermos bottle cooking ... but it's functional for grains, beans, rice, vegetables ... that need to be heated, and maybe need time in the heat to rehydrate, soften and cook.  Lentils, oatmeal, split peas, falafel, quinoa, groats, couscous, pasta, pilaf, etc work great.  For bigger beans, dried limas or favas ... you might have to first partially cook them on the stove ... and let them cook the last 1/2 in the thermos.

First ... you need a steel thermos ... you might succeed w/ a cheap glass flask thermos to test this out ... but for frequent dependable use, you need a steel thermos, Stanley or similar.  I recommend a wide-mouth version for easier cleaning.  I've gotten some good (& moderately priced) ones in the sporting goods area of WalMart (I cringe to recommend them ... am sure you can find as good elsewhere).  I've bought several ... pint & quart sized & larger w/ interchangeable caps for easier use. 

Next ... when you are cooking things up ... just pre-heat the thermos w/ boiling water ... this gets dumped out before filling w/ food.

Then ... depending upon what you are making ... you either put it raw into the thermos ... and add boiling water or broth or whatever

OR ... you get your food to a simmer ... and then dump it into the thermos to keep at a that temperature for hours without wasting any more energy. 

IF you put your old-fashioned oatmeal (not instant) into the thermos & add hot water the evening before ... it'll be ready to eat and hot for breakfast. 

For an experiment ... a friend & I kept 1 batch of oatmeal warm & edible for 3 days ... well ... the 3d morning it was getting pretty tepid ... but that was testing the limits.

You can spice it up ... cinnamon, etc when you make it.

It also lets you make tomorrow's hot lunch, the evening before. 

IF you are using this method for beans, rice etc that will swell enormously when hydrated ... you have to leave room for the expansion.

ALSO ... it's a great way of cooking ahead & keeping foods warm for later ... such as dinner vegetables, rice, etc.

Lots more info online if you google "Thermos Cooking" ... a lot of sites will pop up ... including the obvious one:

Combining this technique w/ using a solar cooker for long-simmering foods (esp large beans, stews, etc) ... and using the Adobe oven outside for 1-2 loaves of bread / week & then a meat dish (poultry, cabrito, etc) as it cools down should allow me to minimize any inside cooking during the hot months (and decrease the amount of air conditioning I'll need).

I suppose it also adds a safety factor if you have small kids in the house ... this can help eliminate the pot handle on the stove that they might pull over on their heads!

Hmmm ... come to think of it ... it might be a great way of making yogurt ... just get the milk to the right temp, add culture ... and put it into the thermos for a day?

I'm always on the lookout for a good recipe that uses thermos cooking. If anyone has a good recipe to share, please post it in the comments (esp if you've improved upon one posted elsewhere :-)


Recommend and Share

4 Recommendations
Sharing outside of Earthineer helps us grow!

Respond to this Article

Login or Sign up to leave a comment

Mary Henderson (HumblePie)

March 10th, 2012 at 8:33am

I have never heard of thermos cooking, but it is a great idea. Since our fall and spring are cool and winter is cold, the supplemental heat from cooking is welcome, but in the summer, this type of cooking would go well with grilling outside.

Thanks for the tip!

Jason Jason (Jason)

March 10th, 2012 at 6:57pm

I tried this with wheat berries, they cooked very well but the taste takes some getting used to, not really bad but not really all that good either. I'm going to plant a few handfuls of hulless oats this spring to get myself some groats. Been wanting to try them but can't find the groats locally. We love oatmeal and if they turn out well a small plot could keep us going all winter.

Jim Staton (Jim Staton)

March 11th, 2012 at 1:28am

This got me to thinking.....

Could you put a sstock pot in a box then squirt some of that expanding foam around it? Basicly making a huge thermos.

There is a yogurt making device like that. It's called the Yogotherm. Available from

Killalunie Killalunie (Killalunie)

March 13th, 2012 at 7:53am

I want to try a solar cooker. For those living in a hot climate, that may be a great energy saver.

Gail Braymen (Lone Star Homestead)

March 17th, 2012 at 8:19am

You don't need a hot climate to use a solar cooker. You just need a clear, sunny day. The ambient temp doesn't matter, but it does help to keep the cooker out of the wind if you can.

Bearclover Bear (Bearclover)

March 17th, 2012 at 9:05am

I do something similar to this when backpacking/snow shoeing. I don't want to carry the added weight of the thermos, so I stick everything in a Ziploc bag and then put it in a small pocket inside my backpack closest to my back or sometimes between the layers of my shirts against my belly- body heat does the rest.

Depending on the contents (and how hungry I get and am willing to eat just about anything), it might be done as early as lunchtime. And the best part is, all I have to do is snip off a corner of the bag and squeeze out the contents. No added weight of utensils and it's easier to "Pack it in, pack it out".

John Alchemist (Alchemist)

March 17th, 2012 at 9:09am

@Desiree... "against my belly- body heat does the rest"
Good Lord! Another babe in coveralls?! I suppose you have an account at Victoria's Secret and Home Depot too! ;-)

Bearclover Bear (Bearclover)

March 17th, 2012 at 9:32am

@The Alchemist: No- I gave up credit cards a few years ago when I realized I had more in my savings than the limit on all my credit cards combined, prefer commando and can pass the Pencil Test, and never found a negligee that looked better on me than skin with no tan lines.

Bearclover Bear (Bearclover)

March 17th, 2012 at 10:02am

Whether you use a thermos, body heat, or "carbeque", knowing how to cook on the move (and what you're willing to eat- texture becomes more important than you'd think) is an important skill to know in case one needs to bug out.

Catherine Lyon (Catherine Lyon)

March 17th, 2012 at 10:07am

@Alchemist,You are too funny!!!!! You are going to get yourself in "hot water" with your wife!! :)

Kevin 2 ( Wild Squirrel 2)

March 17th, 2012 at 12:33pm

@ DB I'm not sure I understand your cooking technique. Could you do a blog with pictures?

John Alchemist (Alchemist)

March 17th, 2012 at 1:24pm

Nah... after 37 years my wife is secure in our marriage. She knows that women are enamoured with me (via humorous flirting only!) and has no worries. The only hot water I ever get into is a hot tub.

I guess that could be another story if I worked at it... hmmm. But you and Desiree are both safe from this old lech - both live too far away! (And yes, being delusional is fun!)

Bearclover Bear (Bearclover)

March 17th, 2012 at 3:22pm

@WS2: :-x

Kevin 2 ( Wild Squirrel 2)

March 17th, 2012 at 4:41pm

Well guys I gave it a shot. I wasn't looking forward to the Johnny Depp movie I would have had to use as a distraction while I read the blog anyway.

Catherine Lyon (Catherine Lyon)

March 17th, 2012 at 9:29pm

Too funny!!! :)

Cantankerous Geezer (Cantankerous Geezer)

April 12th, 2016 at 3:30pm

I've recently been using it to make variations of oatmeal or other grains for breakfast. Just prime the thermos w/ boiling water to heat the thermos itself, pour out the hot water primer, then dump in the oatmeal (slow cooking type) or groats, and some raisins, cranberries, blueberries, etc, 1/4 tsp cinnamon, cocoa, even a little bit of instant coffee, etc, top w/ boiling water, & you have breakfast ready when you wake up. OR ... already in the thermos to take to work or school. You can then add milk or yogurt, but I just eat it hard-core.

Liz Jennings (Liz)

April 13th, 2016 at 11:14am

I have been looking for a way to make yogurt in the wintertime. In the summer I can just leave it outside. I like the idea about the mega thermos, too. (a stock pot with insulation around it)