Take the white rice previously boiled in salted water and pour it into a bowl with olive oil. Cut the mozzarella into cubes and whip the eggs. In the meantime, start to make the supplì with the rice adding, in the center, the mozzarella: shape the mixture of rice and mozzarella in order to create an oval shape. At this point, rub the suppli in the egg and in the breadcrumbs being careful not to break them. Repeat the passage for all the suppli and start heating the frying oil in a pan. As soon as the oil has reached the right temperature, dip the suppli. Drain and serve hot.