Cut each tomato crosswise into twelve one-half inch-thick slices. Season both sides of each slice of tomato and mozzarella with the salt and pepper. Arrange half of the tomato slices in the bottom of a shallow glass or plastic bowl. Top each with 2 basil leaves. Place a slice of mozzarella on top of the basil leave, then top with the remaining tomato slices, then top with the remaining tomato slices and repeat using all the remaining mozzarella and basil. Drizzle with the olive oil, cover and refrigerate for at least 2 hours before serving.
Makes 6 servings