Saving on cooking fuel/energy and time...

One of the easiest ways to save critical fuel is also a time saver.

It's common sense that smaller objects, cook faster. With veggies and meats in stews and soups, simply cutting them smaller for the pot or thinner for the pan will greatly reduce cooking time if fuel is an important factor.

With items like potatoes, it's believed that if you add one of the purpose made 'nails' to the inside and bake the potato it'll cook faster and more evenly. If you nuke potatoes, if you stab it several times it'll cook better if not necessarily faster.

With a hamburger patty, hand made without a press, there's sometimes longer to cook center where it's further from the edge and thicker. One technique to speed up cooking is to make a flattened 'donut' of a patty, finger poke the center so there's a hole through it. It'll cook more evenly. If you puncture a roast repeatedly, it will cook faster, however, you'll be losing moisture. If it's a pot roast, that doesn't matter.

With some starches and definitely with beans, some folks presoak them before beginning to cook them. Adopting somen type noodles makes for quick cooking. (They're thin and cook rapidly.)