Take 2 to 3 pieces aluminum foil. Lay on top of each other for strength or use heavy duty foil. Place 3 to 4 pound beef pot roast in middle. Sprinkle all sides of meat with 1 envelope Liptons Dry Onion Soup Mix, then spoon a can of cream of mushroom soup on top (don't dilute soup). Seal meat in foil.
Place in 13"x9"x2" baking pan (or similar size). Bake at 350 degrees for 2 1/2 to 3 hours. Remove meat and put on platter. Serve juices with meat or thicken for gravy. You can also do this without the mushroom soup. Serves 6 to 8.