Wash sweet potatoes and wrap in foil. Cook in 350°F oven for 1 hour or until tender.
Increase oven temp to 450°F. Spray a 9X13 inch baking pan with cooking spray.
Pat the salmon dry with paper towels, then sprinkle with salt and pepper. Place salmon skin-side up in the prepared pan, tucking thin edges under to make fish a uniform thickness.
Slice onion into strips, and arrange around the salmon. Sprinkle with Worcestershire sauce.
Bake uncovered for 12-15 minutes or until fish flakes easily when pulled at with a fork. Meanwhile, steam green beans.
When done, remove skin from the fish and discard. Transfer salmon to dinner plates, then stir mustard, vinegar, and marjoram into onions.
Top salmon with onions and serve with sweet potatoes, green beans, and applesauce on the side.