Prep ingredients per the instructions above.
Mix the oil, vinegar, olives, garlic, shallots, and oregano in a bowl until fully combined.
Drizzle the inside of the ciabatta with the oil-olive mixture on both halves, and layer with mortadella, ham, mozzarella, salami, and olive mixture.
Mix the sparkling water and lemon.
To serve: Cut muffuletta in half and enjoy with chips, pickle, and sparkling water.