Cut the bread in half lengthways and drizzle with oil. Place on a baking sheet lined with parchment paper and place in the preheated oven on the middle rack. Bake the bread for 10 minutes at 200 °C / 390 °F.
Spread pesto over the bottom of the toasted bread. Place mozzarella on top. And place tomato slices on top of the mozzarella. Season with salt to taste and drizzle with olive oil. Place the second half of the bread on top, cut into two or four pieces, and serve.