Combine the olives, tomatoes, olive oil, pine nuts, lemon juice, pepper, lemon slices, garlic, scallions and onions in an airtight container with a lid. Marinate for 8 hours or up to 7 days to allow the flavors to develop. Add shaved Parmesan just before serving.
Serve alongside antipasti platter and crostini.
Recipe courtesy of Kelsey Nixon