Hugh,
One of your readers was asking about low tech cooking methods. He should search for Haybox Cooker. Articles will be found at Mother Earth News, Instructables, and elsewhere. It’s a very old method of first bringing food to a boil, then setting in an insulated box, and using fine hay to surround the cooking vessel. I’ve used blankets and towels, and it works wonderfully for soup, stew, making your own yogurt, and even for beans. Also, a sun oven is invaluable for low tech inexpensive cooking. Yes, you can and we did buy an expensive one, but our son made one with a box, foil, Styrofoam, and a sheet of glass, and it works just as well. Again search for plans at Instructables. I have made biscuits, bread, stew, soup, beans, lentils, rice, mac & cheese, et cetera. You just have to be sure to orient it to the sun occasionally.
As for good sources of protein that are cheap, lentils, which cook in about 20 minutes, are good as is making your own seitan. Seitan is easy, cheap, and I’ve made it in the solar oven and on the grill. My recipe calls for baking it not boiling it. Beans do require a longer cooking time, but again you can use the haycooker or sun oven, and they are extremely versatile being used plain, in soups, making burgers or loafs, and can be seasoned for lots of variety. Think of hummus or refried beans. They’re easy to make yourself. – B. in Florida