A few weeks ago I attended a thermal cooking course with my kids. It was funded by our local University who are doing some research on it as a modern cooking method and run through a local community hub.
So What Is Thermal Cooking?
“A thermal cooker, or a vacuum flask cooker, is a cooking device that uses thermal insulation to retain heat and cook food without the continuous use of fuel” (Wikipedia).
Soups, stews, casseroles or any food to be simmered (rice and other grains etc) are heated for a short period of time on a conventional flame (gas, electric, open fire) in a pan. Once a high temperature is reached, the pan, with a well-fitting lid, is placed in an insulating bag, box, basket or hole to retain the heat and cook the food gradually inside.
Natural insulators can be used such as straw, hay or cotton or other items repurposed such as a cold box lined with towels. The class we attended helped us sew an insulated cooking bag out of old sleeping bags (see picture above). We will also be making another thermal cooker out of a box (well, I need one for the rice AND the curry!).
Top Thermal Cooking Tips
Cast iron is great at retaining heat so a cast iron pan would be even more effective.
Use a trivet or folded towel as a base inside your thermal bag for stability, to prevent scorching the bag and to prevent any spillages.
If you use dry rather than canned lentils, beans and pulses don’t use tomato based sauces and don’t add salt to the end because tomatoes and salt interfere with the pulses’ ability to soften.
Unlike conventional cooking, thermal cooking won’t boil off liquid, so add less liquid to your pan.
Fill your pan to the top as this retains the heat better - that means thinking about which size pan to use and whether you’ll be batch cooking to freeze meals.
For food safety the temperature of the thermally cooked food mustn’t drop be allowed to drop between 4-61 degrees for more than 2 hours, so use a thermometer to check it at least the first few times you cook. (Use the 2-4-60 phrase to remember this).
Thermal Experience
On the day of the class, we all helped to make a stew, cooking vegetables in stock for five minutes over a medium heat, until it reached a rolling boil. The lid was then placed on the pot, and it was quickly placed inside the insulated bag with it’s insulated lid and the drawstrings tightened around it. The safe temperature for cooked food is over 61 degrees, so this was the minimum the bag needed to keep the food at. surprisingly it kept the food much hotter, even after several hours it was still over 80 degrees.
So far we have experienced stew, butternut squash soup, curry and rice all cooked using this method. All have tasted amazing. But why are such methods making a revival?
Why Thermal Cooking Wins!
It’s easy! 5 minutes prep and the thermal cooker does the rest for you without you being there or needing to do anything!
It cooks to perfection! Unlike slow cookers, which still use fuel, thermal cookers won’t overcook your food, won’t boil dry and won’t boil over because the heat source is the food itself. Potatoes don’t turn to mush and veg is intact!
It’s portable! Your thermal cooker can be taken anywhere: Camping, kids sports games, road trips, picnics. You name it, your thermal cooker is your best friend! Imagine going camping and walking up a mountain all day to come back to your tent and have dinner ready for you!
It’s a fridge too! Thermal cookers can also thermally insulate food to keep it cold.
It’s not just for dinner time! fill your pot the night before and your thermal cooker can have breakfast ready and waiting for you too! Overnight oats never tasted so good!
But This Is Armchair Activist. What’s The Activism Win?
The activism win is the fact that cooking thermally reduces fuel consumption, saving you money and helping the planet. Given the cooking time needed is only on average a 5 minute rolling boil to get your food up to the necessary temperature, this is a vastly reduced use of gas or electric to cook with. Imagine if more of us did this.
Without wanting to start apocalyptic anxiety, it feels comforting to know I can be pretty self sufficient, and in times when fossil fuel companies are making extreme profits, despite international climate warnings from leading scientists, it feels great not being quite so reliant on these greedy fuckers!
Armchair Activism
Simple Activism
Join a group to find out more about this type of cooking and make or buy a thermal cooker!
Step It Up A Notch
Try out some Wonderbag recipes.
Serious Activism
Look into more ways you can reduce your reliance on the fossil fuel industry.