Cut heirloom tomatoes and mozzarella ball each into ¼-inch thick slices. Set aside.
Cut the cherry tomatoes into thin slices, about 3/4 slices per tomato. Set aside.
Cut avocado in half and remove the pit. Peel off the skin of each half. Cut into thin slices. Set aside
Assemble slices of tomatoes, cheese and avocado on a large plate or platter. Season with salt and pepper to taste. Follow with olive oil and balsamic.
Best served day of, but an be stored in airtight container in fridge for up to 2 days.