Preparation Pat steaks dry and cut 3 (1-inch-long) slits 1 inch apart across center cartilage (to keep meat from curling). Put meat between 2 sheets of plastic wrap and pound to 1/4 inch thick with flat side of a meat pounder or with a rolling pin. Discard plastic wrap and sprinkle steaks with 1 teaspoon salt and 1/2 teaspoon pepper (total). Heat 2 tablespoons oil in a 12-inch heavy skillet over moderately high heat until hot but not smoking, then cook steaks in 2 batches, turning over once, until meat is just medium-rare, 2 minutes per batch. Transfer steaks to a platter as cooked and keep warm, loosely covered with foil. (Do not wipe skillet clean.) Add remaining 2 tablespoons oil to skillet and sauté onion and bell pepper over moderately high heat, stirring, until onion is golden, about 4 minutes. Add mushrooms and garlic and sauté, stirring, until mushrooms are golden, about 3 minutes. Add vermouth and cook until evaporated, about 1 minute. Add water and tomatoes with their juice, then reduce heat and simmer, covered, stirring occasionally, until tomatoes and onion are tender, about 5 minutes. Remove lid and cook until most of liquid is evaporated, about 5 minutes. Stir in remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Spoon vegetable sauce on top of steaks.
Preparation Pat steaks dry and cut 3 (1-inch-long) slits 1 inch apart across center cartilage (to keep meat from curling). Put meat between 2 sheets of plastic wrap and pound to 1/4 inch thick with flat side of a meat pounder or with a rolling pin. Discard plastic wrap and sprinkle steaks with 1 teaspoon salt and 1/2 teaspoon pepper (total). Heat 2 tablespoons oil in a 12-inch heavy skillet over moderately high heat until hot but not smoking, then cook steaks in 2 batches, turning over once, until meat is just medium-rare, 2 minutes per batch. Transfer steaks to a platter as cooked and keep warm, loosely covered with foil. (Do not wipe skillet clean.) Add remaining 2 tablespoons oil to skillet and sauté onion and bell pepper over moderately high heat, stirring, until onion is golden, about 4 minutes. Add mushrooms and garlic and sauté, stirring, until mushrooms are golden, about 3 minutes. Add vermouth and cook until evaporated, about 1 minute. Add water and tomatoes with their juice, then reduce heat and simmer, covered, stirring occasionally, until tomatoes and onion are tender, about 5 minutes. Remove lid and cook until most of liquid is evaporated, about 5 minutes. Stir in remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Spoon vegetable sauce on top of steaks.