Preheat broiler. In a large bowl combine tomatoes, onion, capers, basil and mozzarella. Stir in balsamic vinegar and olive oil. Season with salt and pepper. Top toasted bread with the mixture and place on baking sheet. Broil until cheese melts. Serve hot. Alternative: Substitute 1 cup canned northern white beans for cheese and just top toasts with mixture.
Recipe Courtesy of Food Network Kitchens