Tom's Stewed Sirloin, Mushrooms & Onions Marinaded sirloin steak with fresh mushrooms, peppers, and onions in a creamy savory herb sauce. Tom’s Stewed Sirloin, Peppers, Mushrooms & Onions Author: Simple-Food-Solutions.com Ingredients 2 cups chopped onions 1 chopped bell pepper 2 cans cream of mushroom soup 8 ounces fresh sliced mushrooms 1½ lbs thin sliced sirloin