2 cups assorted cherry, grape, and teardrop tomatoes, halved (or quartered if large)
1/2 small red onion, finely chopped
3 tablespoons olive oil plus additional for brushing
3 tablespoons chopped fresh basil
1 1/2 tablespoons balsamic vinegar
1 large loaf focaccia, halved horizontally (reserve half for another use)
1 garlic clove, peeled, halved
1. Combine halved tomatoes, finely chopped onion, 3 tablespoons olive oil, chopped fresh basil, and balsamic vinegar in medium bowl; season tomato topping with salt and pepper. DO AHEAD: Topping can be made 2 hours ahead. Cover and let stand at room temperature, tossing occasionally.
2. Preheat broiler. Place focaccia half, cut side up, on baking sheet; brush bread with olive oil. Toast bread in broiler until top is golden brown, watching closely to avoid burning, about 2 minutes. Immediately rub cut side of bread all over with halved garlic, then cut focaccia crosswise into 4 equal pieces.
3. Top toasted focaccia with tomato mixture and serve.