A haybox cooker is a box full of insulating material that keeps a meal hot enough so that it cooks without having to keep it in the oven or on the stove for hours . It’s a bit like an insulated thermos flask, except rather than coffee or soup it holds a casserole.
Conventional stove top cooking is actually quite energy inefficient; the food simmers as it cooks, but energy has to be continually supplied to the pot to keep the contents warm, as heat is lost through convection and conduction. Imagine if you could minimise this heat loss – you’d need to put less energy into the system. The haybox puts this principle into practise. You heat the pot and food to boiling then put it to a highly insulated container – just like your hot coffee goes into the thermos. The food is cooked slowly by the retained heat and saves a bundle of energy into the bargain.
The haybox can be any kind of box or container that you can pack with insulation and then have room to fit the cooking pot. The box could be a wooden tea chest, an insulated picnic box (‘Esky’) or even a thick cardboard one. As long as it can withstand the (fairly low) cooking temperature and has a tight lid, it’ll work.
‘Haybox’ of course refers t o the original insulating material, which was hay. But pretty much any insulating material will do, and you can even help things along further by lining the inside box walls with reflective foil – again, using the principle of the thermos flask. Try crumpled newspaper, wool, blankets – anything that holds the heat. But don’t use anything which is likely to melt in contact with the pot (some synthetic fibres have low melting points) and of course anything which releases toxic fumes is a non-starter. Pack the box tightly with insulation, put the hot cooking pot in, cover with more insulation, fit a tight-fitting lid and sit back and wait.
That’s the only drawback – the waiting. Food can take up to four times as long to cook food in a hay box than it would in a domestic oven so it’s not something to try if you’re in a rush. And resist the urge to peek, as it will cool down and won’t cook. Finally don’t get the insulating material wet, as it will lose its insulating properties.
Haybox cooking was used a lot during WWII when fuel was scarce. It’s a technique we’ve lost, but if you’ve time, one well worth trying to recapture.