Combine the tomatoes, garlic, onion, basil, extra virgin olive oil, and balsamic vinegar, and salt and pepper in a large bowl and allow this mixture to sit in the refrigerator for at least an hour. This will allow the varying flavors to blend.
Place the sliced bread in the oven on 450 until it is golden brown. While the bread is still warm, place a significant amount of your topping on it, still cold from the refrigerator.
The contrast between the two – hot and cold, toasted and soft – makes the unique texture and taste of this treat even more enjoyable!