Using a plate that has been chilled in the freezer for a few minutes, arrange tomatoes however you would like. Lightly season with salt.
Place the freshly sliced mozzarella cheese on top of the tomatoes. If you can't find fresh mozzarella, try a Kroger Freshmarket or look for it in the specialty cheese location at your local grocery store.
Add the pesto over the cheese or drizzle it, however you prefer to decorate it. You can also add torn fresh basil and small slices of red onion to top it off, if desired. This dish is normally served cold, so you may want to put this in the freezer for just a few minutes after assembling it.