- Pour 1/2 cup teriyaki sauce over pork in large resealable plastic food storage bag. Press air out of bag; close top securely. Turn bag over several times to coat pork. Marinate pork in refrigerator for at least 1 hour, turning bag over occasionally.
- Prepare grill with cover for two-zone cooking (direct and indirect heat).
- Remove pork from marinade; discard marinade. Pat pork dry with paper towels and rub both sides with sesame oil.
- Grill pork over direct hot heat, 3 to 4 minutes on each side to sear pork.
- Move pork to section of grill with indirect heat. Cover and cook 10 minutes.
- Meanwhile, combine remaining 1/2 cup teriyaki sauce, hoisin and black pepper and set aside 1/4 cup sauce mixture.
- Brush both sides of pork with remaining sauce mixture. Cook, uncovered, 5 to 10 minutes longer, or until meat thermometer inserted in thickest part of pork registers 145°F., turning and brushing with sauce occasionally.
- Remove pork to serving platter. Drizzle with reserved 1/4 cup sauce; sprinkle with green onion. Let rest 5 minutes before serving.