I really should have explained this method of cooking before so here goes. The principle of cooking with a hay box is a simple one. To retain the heat in the food after bringing it to the boil on a normal cooker so as to finish cooking it using no electric or gas. This is achieved by making yourself a hay box.
The Hay box can be made out of many different materials (try googling it and you will see the wide range of them out there). Traditionally it was a wooden box with a good fitting lid, where your cooking pot with a tight-fitting lid would be placed. Then hay would be used to insulate all around the pot (top, bottom and sides) thus keeping the pot hot whilst the food cooks.
I have never used actual hay in any of my hay boxes. Todays materials are much better at keeping in the heat than hay. My best hay box (sadly lost in a move) was picked up at a carboot for 50p. It was a very large rigid cool box into which I could place my hot casserole dish (with tight-fitting lid), with plenty of room for one pillow under it, one pillow on top and stuffing from an old sleeping bag all around. It worked a treat.
I have got a friend who swears hers is great which consists of a heavy-duty cardboard box with her large thermos flask (which she uses instead of a saucepan or casserole) wrapped up in an old duvet. I have not had dinner at hers so I can’t vouch for it but in principle it should work.
It does take longer to cook with a hay box and I have found the best things to cook are stocks, soups and casseroles. These tend to need quite a long time simmering on a cooker and that costs money! So a quick 5 to 10 min boil then into the hay box for as long as needed. Now there is the nub…How long is needed…How long is a bit of string? It all depends how your hay box is constructed and what you are cooking so it’s a bit trial and error but there is loads of info out there on the internet.
My veggie soup (recipe coming soon) would take 40 mins of simmering (after bring to the boil) on the cooker but takes approx 2 hours in my hay box. At least with the hay box it’s free cooking and no need to keep looking at it or stirring. In fact the rule of the hay box is DON’T LOOK AT IT you’ll let the heat out.
Personally I would not cook meat/ fish this way. I only use it for vegetarian meals and NEVER for rice (far too dangerous).
Go on give it a go, it’s a very cheap way of doing veggie meals. It’s also a fantastic way of doing meals if you are camping!