Place the balsamic vinegar in a a small sauce pan over low heat. Allow to simmer until it has been reduced by 1/3rd. It's done when the vinegar coats the back of a spoon.
Assemble the Salad
Cut the heirloom tomatoes into thin slices and halve the cherry tomatoes. Assemble them on a white plate and add shredded motzerella and basil leaves. Add the olive oil balsamic reduction and season with salt and pepper.
This salad is best eaten right after it has been prepped.