Hay box, or thermal cooking, has probably been around almost as long as the species has been cooking with fire, and could be one of the easiest cooking alternatives to put together in an emergency.
The concept is simple: a container of some type is filled with an insulating material to hold in heat. The concept is so named because in earlier times, hay would have been used for the insulation. Food is put into a heavy pot, such as an enameled cast iron dutch oven, and brought to a boil on another heat source for anywhere from a few minutes up to 20 (the latter for dried beans). The pot is then put into the box, completely surrounded by a thick layer of the insulation, and left to cook using retained heat. Left undisturbed, the cooked food will stay hot for hours. Hay box cooking works like a slow cooker, but without the electricity.
In a pinch, a large cardboard box or plastic tote could be used for the container to hold the insulation, which could be pillows, towels, blankets or even coats or t-shirts – the bigger, and/or thicker, the better. You want to really hold the heat, and you want as little of it to escape as possible if you have to open it before the food is ready, so start with pillows, blankets, or coats, if you have a container large enough. If not, use a smaller pan, though you probably don’t want to use anything smaller than two-liter, or about two quarts.
An ice chest, if available, would provide better insulation. I will admit to having tried something on this order, but wanted more consistent results, and ended up purchasing several of what are available online as thermal cookers. (Because of their insulation, thermal cookers can also be used to keep cold things cold.)
For safety, a meat thermometer is a always a good idea. It’s even more important in cooking with any of the alternative methods, which are all very different than using a traditional stove or oven. In thermal cooking, you may need to know if the food has cooled down enough to be in the danger zone by the time you get to it (40 to 140 degrees). However, this isn’t likely to happen, as long as you follow the guidelines / instructions for use.
Like all alternative cooking methods, hay box cooking has its strengths and drawbacks. It does require an external heat source, which may not be easily accessible, particularly if utility services are out for an extended period of time.
A big advantage this type of cooking has over solar cooking is that it can be done at any time of the day or night – even overnight.
Haybox cooking works very well for foods with a fair amount of liquid, such as soups and stews. But with a little ingenuity, and a watertight container or two, a wider variety of foods can be cooked this way. “Omelets” are quick and easy, too: poured into a sandwich bag, preferably one with a zipper, and left in the heated water for a few minutes to cook. It’s helpful to massage the bag after a minute or so for more even cooking; otherwise, it’s no fuss, no muss – you can even eat it right out of the bag.
One of my favorite things to cook in a thermal cooker is potatoes – either for mashing or potato salad. Scrubbed, bad spots / eyes removed and tossed in whole, they have a denser texture than traditionally boiled potatoes, which makes them especially nice for potato salad. It’s about the easiest way to cook potatoes: Fill the pot with them, add water, bring to a boil for two minutes, put the pan into the cooker and come back in a half-hour or so – they’ll be cooked to perfection. They can be mashed in the pot, and returned immediately to the hay box or thermal cooker to stay warm until the meal is served. Now you can offer to bring the mashed potatoes to the next holiday meal, taking a time-consuming, last-minute task off of the hosts’ hands – which they’ll probably really appreciate.
Word to the wise: Whether you have a purchased thermal cooker or are using something improvised, it would make sense to give it a test run before the big day, so you know what to expect – you wouldn’t want to offer friends and family cold potatoes! Thermal cookers can be very handy for any kind of social gatherings, as well as for families who may be home for dinner at different times, for first responders and others who may have to leave at a moment’s notice or for anyone who wants to save a little energy and effort while enjoying a healthy, home-cooked meal.