Preheat oven to 400℉. Brush olive oil on both sides of the pitas.
Place a pita on a cookie sheet. Spoon tomato sauce on top of the pita in an even layer. Layer tomato slices, basil leaves, and mozzarella on top of the sauce. Repeat this process until all of the pitas are prepared.
Cook for 10-12 minutes, until the mozzarella is melted and begins to brown. Remove from oven. You may need to cook a couple at a time, depending on the size of your oven. I can do two pitas at a time.
Sprinkle with salt, pepper and balsamic vinegar to taste before serving.