Start by preparing the steak, click Quick Skillet Steak with Mushrooms and Onions for the recipe.
Preheat oven to 425° or set your broiler to low.
Once the steak is cooked and ready, cut bread into 4 pieces. Divide steak and mushrooms evenly between four sandwiches and place a slice of cheese on each one. Place sandwiches on a cookie sheet and heat in the oven or broiler until the cheese melts; 2 – 3 minutes, careful not to burn if using the broiler.