Bite-sized balls of mozzarella, known as bocconcini, are ideal for making this colorful salad. Look for them in Italian delicatessens, or cut larger mozzarella balls into small chunks. If possible, seek out mozzarella di bufala, made from water buffalo's milk; a specialty of central and southern Italy, it is a softer, creamier mozzarella than that made from cow's milk.
