Prepare a marinade using pesto, vinegar, oil, salt and pepper. Drain the mozzarella balls and let them steep overnight in the marinade.
Wash tomatoes and basil. Alternately stick a tomato, a basil leaf, a marinated mozzarella ball, another basil leaf and another tomato on a toothpick. Arrange the skewers on a plate and nap with the leftover marinade (cover)