In a scenario where cooking fuel may be a limited or be a difficult to replace commodity, learning to cook with the least amount of fuel is as simple as learning to prep the food well and keep an eye on the fire.
Consider this, most modern cook books are assuming you have an electric stove. What if the time comes when you don’t have electricity? I have a cookbook from the kitchens of turn of the century southern cooks. The heating instructions state use a moderate or hot oven, a slow or rapid boil, or your best judgment. These instructions assume you have a wood or coal burning stove. If you want to find a cookbook for a fireplace or propane stove, you could look for a good thorough camping or RV cookbook. Keep your eyes open at yard sales and estate sales. In an older home there my be older information from a time when the first wife used a gas range or even a wood stove!
Either, wood stove or propane burner, the fuel will heat the pot and the hot pot will cook the food. High heat is not needed to complete the process. The best tip I can offer is read the recipe first. Be prepared to follow the instructions and maybe improve on an older recipe with your experience.
Once a pot of water comes to a boil, most recipes ask you to reduce the heat and simmer for a prescribed time. Wood and gas stoves cook faster. You may have to add water or reduce cooking time. Testing and practice make the best cooks.
Once you have a good cookbook and you are confident from the practicing of the recipes, there are prepping tips that can help save fuel.
Cooking beans requires soaking the beans. Be sure they are well softened before putting them on the heat. If you want to speed up the soaking time and have the use of propane for easy on and off control, you can cover the beans with water, bring to a boil and maintain a boil for 5 minutes then turn off the heat. Cover the beans to keep the heat in and let them stand for an hour to soften.
Most canning recipes call for the blanching of tomatoes and other vegetables before jarring. You don’t want to boil a vat of water. Boil no more than enough to cover the tomatoes plus one inch. Dip in two or three at a time and remove quickly with a slotted spoon. Blanch all the tomatoes before going on to the next step.
Steaming vegetables takes less time than boiling and less oil than frying. To reduce the time on the stove, prepare the vegetables first. Peel away the tough skins of zucchini, other squashes, celery, potatoes, yams, carrots. Cut the vegetables into bite sized pieces. For broccoli and cauliflower, cut a cross in the stem before steaming.
Use a steamer. I know you have seen these things, maybe you didn’t know what they were. A steamer is a three or four footed metal circle that has hinged leaves all around. It has holes to let the steam through. Often they have a center handle. You unfold the steamer leaves, place it in a pot, it adjusts to the pot size. Add vegetables and water then cover the pot with a lid and turn on the heat. Don’t go anywhere. It only takes about ten to fifteen minutes to steam to completion. Steam fruits pretty much the same way. Once the water is boiling and you see the vegetables wilting under the heat, you can turn off the propane and let the hot pot do the rest of the work.
If you can’t find a proper steamer, a large pot and a metal colander will work, clumsily, but it will work.
For more information, look into this site with tips to reduce cooking fuel,