Preheat oven to 400°.
Heat a medium nonstick skillet over medium heat. Coat pan with cooking spray. Add leek to pan; cook 5 minutes or until tender. Add 2 tablespoons wine; cook 1 minute. Arrange leek mixture in bottom of an 11 x 7-inch glass or ceramic baking dish coated with cooking spray.
Spread Duxelles evenly over leek mixture. Place fish on top of Duxelles; sprinkle with salt. Drizzle with remaining 6 tablespoons wine. Bake at 400° for 12 minutes or until desired degree of doneness. Serve fish with leeks and cooking liquid.
Sustainable Choice: Arctic char is a smart option when wild salmon isn't available.