1. Whisk together olive oil and pesto and allow to sit for at least 10 minutes.
2. Slice tomatoes and mozzarella into approximately 1/4" (0.6 cm) thick slices.
3. On a plate or platter, alternate overlapping slices of tomato with mozzarella cheese. Drizzle the olive oil/ pesto mixture over the top and season with salt and pepper.
Best served immediately, but you can also save it for later. This is a great side accompanied by both red and white meats or fresh vegetables.