Slice your tomatoes, into ¼” slices, then slice your mozzarella in half, then create ⅛-¼” half-moon slices.
On a medium plate, layer the tomatoes and mozzarella in a circle, in between whole basil leaves, or if you have an herb cutter, use them to shred the basil into strips and sprinkle over the top.
Drizzle with olive oil, then sprinkle with salt and freshly ground peppercorns.