Remove giblets, neck, and excess fat from duck. Make small slits along breast of duck and place in a large pot filled in water. Cover, bring to a boil, reduce and allow to simmer for 10-15 minutes. Remove duck from pot allowing excess fat to drain out.
Preheat grill for high heat. Place duck in a shallow glass dish and pat dry with paper towels. Season with garlic, pepper, and salt.
Tie legs and wings with kitchen twine. Place in grill over direct high heat and cook for 30 minutes. Baste with 3 tablespoons of hoisin sauce and allow to cook for a remaining 10-15 minutes.
Remove and allow duck to rest for 10 minutes before slicing. Slice and serve with warmed hoisin sauce on top.