1Heat gas or charcoal grill. In small bowl, mix syrup, mustard and onions. Reserve 3 tablespoons syrup mixture in separate small microwavable bowl. Brush remaining mixture on ham.
2Place ham on grill. Cover grill; cook over medium heat 8 to 10 minutes, turning once, until browned. Microwave reserved syrup mixture uncovered on High 20 to 30 seconds or until hot. Place ham on serving platter; pour syrup mixture over ham.