Blanch the shredded celtuce until cooked, then drain excess water, and set aside.
Cut the grouper fish fillet into thick slices, marinate with the marinating ingredients, and set aside.
Place the celtuce on a plate, then add the slices of grouper fish fillet on top. Steam over high heat for 8 minutes. Remove from the steamer, add the shredded green onions and red peppers, and finally drizzle with hot oil and the prepared soy sauce mixture before serving.
Tips: After returning home, make sure to remove any remaining blood vessels and clots inside the fish belly. This will help reduce the fishy smell.