Three of the TrashBack – Rewards for Rubbish team members recently attended an Earthchild Project workshop on how to make and use a “Hot Box” or “Wonder bag”. These clever cooking contraptions are made from compartmentalised cloth sewn in the shape of a large hollowed-out pumpkin, which is then filled with recycled polystyrene balls. Now you might be thinking that polystyrene is terrible stuff, and it is, but there are alternatives. The hot box can also be stuffed with many more desirable materials, including old shredded recycled plastic, fabric, down feathers, straw, newspaper or even barley (although the latter may be rather heavy so will likely need to be mixed with straw, for example).
The idea of the Hot Box is to significantly reduce the energy needed for cooking, by using the power of insulation to retain the initial heat necessary to bring the food to the boil. Once the heat source has been turned off, this initial heat is contained in the Hot Box, cooking the food slowly over a longer period of time. Slow food is definitely the way forward, in fact, everyone should be using these!
To cook with the wonder bag takes a little planning ahead, but can actually save time, energy and reduce the need to watch a hot stove. Furthermore, almost anything can be cooked in this way. To give you an example, brown rice cooked in a Hot Box is super simple. The correct ratio of rice and water is brought to the boil (for about 5 minutes, until the lid is piping hot) and then the stove can be turned off. The hot pot is then placed straight into the awaiting Hot Box, and about 2 hours later the rice is perfect and ready to eat! You may think this is a long time to wait, but let me just remind you that you can stuff and sew a new Hot Box in this time, and you don’t have to worry about anything burning. Some bigger meals and stews may take a few more minutes of stove time, but not much, meaning that every meal cooked in this way is an energy saving win!