Combine soy sauce, wasabi, ginger, and sesame oil in a large zip-top plastic bag; add fish. Seal and marinate at room temperature 5 minutes, turning bag occassionally to coat. Remove fish from the bag, reserving marinade.

While fish marinates, heat a large non-stick skillet coated with cooking spray over medium-high heat. Add fish; cook 3 minutes. Turn fish over. Reduce heat to medium, cook 8 minutes or until done.

Yeilds: 4 servings (1 fillet per serving)