Cook the pasta in boiling salted water for about 8 minutes, then drain. In the meantime drain the mozzarella. Peel and finely dice the onion. Knead minced meat, onion, egg and breadcrumbs. Season to taste with salt and pepper.
Form minced meat into small balls. Work in 1 ball of mozzarella each. Fry the balls in 2 tablespoons of hot olive oil for about 5 minutes, turning them over, and put them aside. In the meantime peel the garlic and press it through a garlic press. Clean, wash and slice the tomatoes. Halve the olives as desired. Heat the remaining olive oil in the frying fat. Steam tomatoes and garlic for about 10 minutes. Add vegetable juice, meatballs and olives, cook for 5 minutes. Season to taste with salt and pepper.
Heat the remaining olive oil in the frying fat. Steam tomatoes and garlic for about 10 minutes. Add vegetable juice, meatballs and olives, cook for 5 minutes. Season to taste with salt and pepper. Add remaining mozzarella balls to the sauce. Serve the pasta and meatballs with the sauce. Serve garnished with parsley