In a glass measuring cup, mix maple syrup, soy sauce, lemon juice, mustard and ginger. Mixing well.
Cut salmon into 4 serving portions and place in a shallow bowl. Drizzle all but 1/4 cup of marinade over salmon. Set aside remaining marinade to serve over cooked fish. Refrigerate fish for at least 30 minutes.
Pre-heat oven to 400 degrees. Place chilled salmon in baking dish, skin side down. Bake for about 15 minutes, basting occasionally. Salmon can overcook within a one minute period, so watch fish as it nears completion.
Remove from oven, add remaining marinade and sprinkle with scallions.
Serve immediately