Ingredients
- 3 medium onions, thinly sliced (3 cups)
- 1/2 stick (1/4 cup) unsalted butter
- 10 oz mushrooms, thinly sliced (4 cups)
- 1 1/2 lb sliced rare roast beef, cut into 1-inch pieces (5 cups) and pieces separated
- 1/4 cup water
- 4 (6-inch-long) sections soft Italian bread
- 1/2 lb sliced provolone or mild Cheddar
Directions
- Preheat broiler.
- Cook onions in butter in a 12-inch heavy skillet over moderately high heat, stirring occasionally, until pale golden, about 5 to 7 minutes. Add mushrooms and cook, stirring occasionally, until mushrooms are golden, 5 to 7 minutes. Stir in beef, water, and salt and pepper to taste and cook, stirring, until heated through, about 1 minute.
- Halve bread horizontally without cutting all the way through and open cut sides, then put bread in a shallow baking pan. Divide beef mixture evenly among bread and top with cheese. Broil 6 inches from heat until cheese is melted, 1 to 2 minutes.
