In a large bowl, combine the first eight ingredients. Crumble pork and beef over mixture; mix well. Cut mozzarella into eighteen 1/2-in. cubes. Divide meat mixture into 18 portions; shape each around a cheese cube. , In a large skillet, cook meatballs in oil in batches until a thermometer inserted in the meat reads 160°; drain. In a large saucepan, heat marinara sauce; add meatballs and heat through. Serve over pasta. Freeze option: Freeze cooled meatball mixture in freezer containers. To use, partially thaw in refrigerator overnight. Heat through in a covered saucepan, gently stirring and adding a little water if necessary. Serve with pasta.