Take two pieces of sourdough and drizzle one side of both with olive oil. On same side sprinkle both with a generous amount of basil and garlic. Place this side down on toaster oven baking tray. Place grated mozzarella on each piece of bread on the side you did not apply oil. Cover the mozzarella on both sides with tomato slices and place red onions on top of the tomato on one side only. Sprinkle basil and garlic over top of both sides and place tray in toaster oven set at highest bake temperature (400 F). Let cheese melt and bread toast. To assemble use the onion half as your bottom.