Note: In a bowl, mix pesto with olive oil and blend well with a whisk. Slice the Mozzarella in 8 equal portions and set aside. Pour the basil oil on top, making sure that it covers all the slices. Season with the pepper only. Allow the Mozzarella marinate for 30 minutes in the refrigerator. Roast the pistachios in a 350 °F (180 °C) oven for 10 minutes or until they turn slightly brown in color. To assemble the salad, arrange the different tomatoes in the center of the plate. Place a slice of Mozzarella on top of tomatoes. Repeat previous steps, stacking tomatoes and another slice of cheese ending with tomatoes. Sprinkle with the pistachios. Drizzle with basil oil and a few drops of balsamic. Drizzle some basil oil and any remaining balsamic vinegar on top of the salad. Season with fresh ground pepper. Garnish with a sprig of basil and serve with fresh foccaccia croutons.