Preheat oven to 400 degrees. In 12-inch nonstick skillet, heat olive oil on medium 1 minute. Add onion; cover and cook 8 to 10 minutes or until onion is tender and golden brown, stirring occasionally.
Meanwhile, grease 13″x 9″ glass baking dish. With tweezers, remove any bones from salmon pieces. Place salmon, rounded sides up, in baking dish. In cup, stir together curry powder, Dijon mustard, and 2 teaspoons water; use to brush evenly over salmon.
Roast salmon, without turning over, 15 minutes or just until opaque throughout.
While salmon roasts, add ginger and cumin to onion in skillet, and cook 1 minute, stirring. Add cabbage and 1/4 teaspoon salt; cover and cook 11 to 13 minutes or until cabbage is just tender and starts to brown, stirring occasionally.
To serve, spoon cabbage mixture onto 4 dinner plates; top with salmon.