Wash and dry the tomatoes. Cut a lid from the top of each tomato and hollow out the insides. Season the hollowed tomatoes with salt and pepper.
Finely dice the mozzarella into small cubes.
In a bowl, combine the cold-pressed olive oil, wine vinegar, and mozzarella whey. Season with salt and pepper and stir in the roughly chopped basil leaves.
Add the mozzarella cubes to the marinade and let them steep for at least 1 hour.
Pour the mozzarella mixture into the hollowed-out tomatoes and serve, garnished with basil leaves.