1.Wash hands well with soap and warm water. Wash all produce and chop as directed.
2.Preheat grill to medium high.
3.Place fish in a shallow dish, pour ½ cup of the sauce over the fish. Cover the dish and allow to marinate in the refrigerator for 1-2 hours. Discard marinade once used.
4.Grease grill grates right before cooking.
5.Place fish on the grill, cook for 4-5 minute on each side until it is white and flaky and reaches an internal temperature of 145ºF.
6.Grill pineapple and onion for about 5 minutes on each side, until softened. Remove from heat and brush with teriyaki sauce.
7.Serve by topping the fish filet with 1-2 slices each of pineapple and onion. Sprinkle with sesame seeds (if using).