Gremolata is a raw Italian condiment of finely chopped parsley, garlic, and lemon zest, traditionally in a ratio of about one part garlic to two parts each parsley and zest. It comes from Milanese cooking in Lombardy, where it's classically spooned over osso buco, its sharp, herbaceous bite cutting through the richness of the slow-braised veal.
It's used as a finishing touch, sprinkled on just before serving over grilled or braised meats, fish, and vegetables, or worked into marinades, rubs, and toppings for crostini and bruschetta. Some versions swap in mint or oregano, or use orange or lime zest instead of lemon.
It's related to, but distinct from, Argentine chimichurri (parsley, garlic, oil, and vinegar) and Greek ladolemono (lemon, garlic, and oregano in olive oil); all three share a parsley-garlic base but differ in fat and acid.