Hobo dinners are a classic scout meal. Start by taking a piece of aluminum foil, about a foot or 16" long. Put a few slices of onion on the bottom, and then some thin slices of pealed potatoes and carrots in a small pile in the middle of the foil. Then place a raw hamburger patty on top of that. At this point, season with salt, pepper, and other spices if you like. You can finish it off with other soft vegetables if you like. Red bell peppers is a favorite. Wrap the whole thing up in the foil, and put a second layer of foil around it too.
Toss in the warm coals of a fire that has mostly burned down. After ten minutes or so, flip it over for a few minutes. If the coals are too hot, you will get crispy critters - burnt offerings.