6 tablespoons (3/4 stick) butter 2 to 3 medium-sized onions, chopped (about 2 cups) 8 ounces Portobello mushrooms, stems on, cut into 1/8-inch-thick slices (4 to 5 medium-sized mushrooms) 1/4 cup bottled steak sauce 1 (8- to 10-ounce) loaf French bread, cut in half lengthwise 1 (6-ounce) package sliced provolone cheese

1. Preheat oven to broil. In a large skillet, melt butter over medium-high heat.
2. Sauté onions 6 to 8 minutes, until softened. Add mushrooms, reduce heat to medium, and continue cooking 3 to 5 minutes, turning often. Pour steak sauce over onions and mushrooms; stir.
3. Divide mixture evenly over bread halves and top with cheese slices. Broil 5 to 8 minutes, or until cheese is melted and top is golden. Use a serrated knife to cut diagonally into serving-sized pieces.