Combine dressing and soy sauce in a large zipper bag. Add salmon and shake to coat. Marinate in the refrigerator at least one hour and up to one day.

Preheat broiler and spray a glass baking dish with cooking spray. Arrange salmon pieces in dish so they are not touching one another and pour marinade over fish. Broil seven to nine minutes, until tops are brown and fish flakes easily with a fork, spooning marinade over fish after four minutes. Transfer to a serving platter and garnish with toasted sesame seeds.