In a large mixing bowl, toss the tomatoes, sliced
onions, kalamata olives, 2 tablespoons of olive oil, 1 tablespoon of white balsamic vinegar, 2 tablespoons of parsley, and some black pepper. Mix well and pour into a baking dish. Bake 20 to 25 minutes, or until onions carmelize and tomatoes brown. Pull from the oven and set aside.