In a bowl, toss together the pesto and mozzarella balls. To make the vinaigrette. Combine all ingredients in a glass jar and shake, or whisk to combine. Season with salt and pepper.3 To assemble, thread the prosciutto (if using), melon balls, cheese, and basil onto skewers. You can mix and match your skewers or make them all the same. Arrange on a serving plate and serve drizzled with the vinaigrette.