Place garlic, ginger, and onion in the bowl of a blender. Add soy sauce, sesame oil, Worcestershire sauce, meat tenderizer, and sugar. Puree until smooth.
Pour the marinade into a resealable plastic bag or glass bowl. Score the flank steak and place into the marinade. Marinate overnight in the refrigerator.
Preheat a grill for medium-high heat.
Grill steak on preheated grill to desired doneness, about 7 minutes per side for medium.
