Asian BBQ Butterflied Lamb Leg

2/3 cup hoisin sauce
 6 tablespoons rice vinegar
 1/2 cup minced green onions
 1/4 cup mushroom soy sauce
 4 tablespoons minced garlic
 2 tablespoons honey
 1/2 teaspoon sesame oil
 1 tablespoon toasted sesame seeds
 1/2 teaspoon ground white pepper
 1/2 teaspoon freshly ground black pepper
 1  boneless butterflied leg of lamb

In a large resealable plastic bag, mix hoisin sauce, rice vinegar, green onions, mushroom soy sauce, garlic, honey, sesame oil, sesame seeds, white pepper, and black pepper. Place lamb in bag, seal, and turn to coat. Refrigerate for 8 hours, or overnight.
Preheat grill for high heat.
Oil the grill grate. Place lamb on the grill, and discard marinade. Cook 15 minutes on each side, to a minimum internal temperature of 145 degrees F (63 degrees C), or to desired doneness. Transfer meat to a serving platter, and allow it to rest for 20 minutes before slicing and serving.