Haybox or retained heat cooking is simply cooking a liquid based food like a soup or stew in it's own heat. During WWII cooking oil was rationed for the war effort this method became popular as a way to conserve cooking fuel. They used hay in a box because the air spaces in the hay trapped in heat and allowed the soup or stew to cook in it's own heat. Anything like hay, shredded news paper, rice hulls, cotton balls, corn husks etc will work as long as it packs loose and creats air spaces.
Step 1: Get a container
Pretty much anything will do, i got this box at a army surplus store. A cardboard box will do as well, some people have even dug a hole in the ground and used that.
Step 2: Optional
If you have a wooden or metal box you might want to line it with that emergency blanket material, this helps trap even more heat.
Step 3: Get your material ready
Get the material your using. In this case i use shredded newspaper because it's everywhere and it works well.
Step 4: Line the box
Put a layer on the bottom of the box a bout 2 to 3 inches deep. This is what your stew will rest on.
Step 5: Prepare your soup or stew
I don't have a pic for this step, but i hope it will be clear. Take the pot or kettle you will be using, make sure it has a lid, the tighter the fit the better. Put all the ingredients in the pot with water or broth,try to keep it as full as possible, the fuller the pot the larger the mass and therefore it holds more heat and cooks better. That's why this method is good for cooking for large amounts of people. Turn on the heat and get it to a roiling boil ( a good strong boil) and let it go for a bit. Some ingredients should be simmered for a time to increase the heat like beans, they should be simmered a bout 15 minutes after it boils. Potatoes or rice 5 or 10 minutes