Could You Ditch Your Oven?

With the nights starting to draw in, and the days becoming cooler, the thought of warming stews and steaming bowls of porridge is tempting me back into the kitchen. However, after a summer of freak weather events and with energy prices rocketing, I have a strengthened resolve to reduce our family’s energy usage and reliance on fossil fuels. So without investing in a wood powered oven, will stews and casseroles, cooked for hours on the hob, be a thing of the past?

Enter the concept of thermal cooking! This involves bringing a pot of food to the boil before transferring it to an insulated box or bag, where the food continues to cook slowly, without the need for an external heat source.

An ancient practice
This concept is not a new one. The earliest known thermal cooker dates all the way back to the medieval period in Europe; food would be heated in an earthenware pot before being placed in another larger pot, a box or even a hole in ground. It would be insulated using moss, hay or other dry material and then covered, allowing the food to cook without using fuel, or needing to be watched over. Hayboxes (a box filled with hay or straw into which the cooking pot is placed) were also commonly used during World War II, to help conserve rationed cooking fuel.

Build your own thermal cooker
In it’s simplest form, not very much has changed. It is fairly easy to build your own version of a thermal cooker at home, without the need for specialist equipment. Firstly, you will need a lidded box or container, large enough to fit your saucepan with space for insulation. Many people use old laundry baskets, blanket boxes or even hard-plastic cool boxes (normally used for camping). You will then need an insulating material. Hay and straw work, but blankets and old duvets or pillows are probably a less messy alternative! Arrange your box so there is an insulating layer covering the bottom, and then place in a tea-towel or trivet to stop the hot pan from singeing the material. Short-handled pans are generally recommended (these are easier to fit into the thermal cookers), and pans must be metal with a well fitting lid. Cast iron pans are particularly well suited due to their heat retention properties. All food cooked in this way should be brought to the boil and boiled for at least 10 minutes, to reduce the risk of food poisoning. Once boiled, the saucepan can be transferred into the box, wrapped around with the remaining insulating material and left. Cooking times are generally 3 times what you would expect for conventional cooking.

Or buy a thermal bag
Other options are readily available to buy as well, including the wonderful “Wonderbag”. This company was founded in 2008 as a solution to the South African energy shortage, which forced blackouts across the country. It aimed to allow families to continue cooking daily meals, even with the absence of power. As a business, they support all 17 UN Sustainable Devlopment Goals and have a hugely positive social impact. With each Wonderbag purchased, money is given to help provide bags to families struggling across the world. For example, during 2020, 60,000 Wonderbags were distributed across South Africa, and in 2022, 2,500 were donated to families in Ukraine. With Woman and Girls disproportionately burdened with the unpaid labour of cooking and collecting firewood, these donations can have hugely positive impacts on their lives. Whether it is giving them more time for education or paid work, or improving their health by reducing the length of time they have to cook over a smoky open fire, these simple bags can make a big difference. For more information about their work and products, check out wonderbagworld.com

TOP TIPS TO GET STARTED IN THERMAL COOKING

• Depending on what you are cooking, initial boiling times may need to be longer. Root vegetables and large pieces of meat will need boiling for longer, so if you are looking to further reduce cooking times, try cutting food into smaller chunks or even grating/mincing.
  
• To ensure your pan retains as much heat as possible, try and fill it as full as you can. If you need to cook a smaller amount, it’s better to use a smaller pan to reduce the surface area over which heat is lost.
  
• There are many recipes out there specifically written for thermal cookers (try googling wonderbag, haybox or thermal cooking recipes, or joining Facebook groups for tips and recipes). However, most slow cooker recipes will also be suitable, with only small changes needed.
  
• As well as stews, curries, dahls and casseroles, you can also use these cookers to make yoghurt! Follow a yoghurt recipe, but instead of transferring to a yoghurt maker or warm airing cupboard, place the saucepan into your thermal cooker.
  
• Why not take your thermal cooker on holiday? Smaller, portable versions are perfect for camping or picnics. Try preparing a meal on the stove before you set off and then taking it with you whilst it cooks; the perfect way to have a warm meal without the need to light the stove. They can also be used as a cool bag – the insulating material helps keep cold things cold as well as hot things hot!
  

Our thermal cooker is now an integral part of our weekly cooking. It does take a little more planning but I love experimenting with new recipes and it has been perfect for batch cooking meals for our family. So whether you’re trying to reduce your energy bills, living off-grid and needing to conserve fuel supplies, or just wanting to do your bit to help the planet, perhaps this might be an old cooking method to resurrect!