Heat oven to 300 degrees. Butter round steak on both sides and place on a sheet of heavy duty foil.

Sprinkle with onion soup mix and mushrooms. Fold up foil in drugstore wrap, place on broiler pan in the middle of the oven. Bake for 2 hours.

Notes: Scrubbed baking potatoes can be put in the oven at the same time, add a salad and dinner is ready.