Combine soy, sherry, sugar, vinegar, ginger, garlic and spice powder in plastic food-storage bag; squeeze to mix. Remove and reserve half of the marinade. Add salmon to bag; seal and refrigerate 1 hour.
Oil grid. Grill salmon, skin side down, over medium- hot coals 6 to 8 minutes, until cooked. Or broil, skin side down, 6 inches from heat 6 minutes, until cooked.
Toss noodles, peanut sauce, reserved marinade and onion in bowl. Place equal amount of noodles on 4 plates. Top with salmon. Makes 4 servings.