My father called them "Cowboy packets" so I do, too. I fold over about a 24" sheet of heavy duty foil to start off.
Rub with a little olive oil to prevent sticking. I usually flatten a bit of ground beef, not quite as large as a hamburger, in the middle. Top with diced, peeled potatoes, chopped or sliced onions, carrots - about 1/2 " thick sliced on an angle. Ground pepper and Lary's seasoned salt. Sometimes a squirt of Swwt Baby Ray BBQ sauce.
Then seal up the bundle but not too tight or flat - allow some room for the steam.
Cooks in 15 or 20 minutes on the grill grate.