In a shallow dish, combine the first 7 ingredients; add steak and turn to coat. Cover and refrigerate overnight. , Drain and discard marinade. Grill steak, covered, over medium heat for 6-7 minutes on each side or until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°). Let stand for 5 minutes., Thinly slice steak across the grain. Drizzle with hoisin sauce; garnish with onions. Sprinkle with sesame seeds if desired.