Spray a baking dish with non-stick spray and place salmon in skin side down. Rub honey mustard mixture all over the top and sides of the salmon. Bake for 12-15 minutes.After removing from the oven, gently flip each fillet over and remove the skin using a fork.
(Optional: Make pickled onions for salad) Place onions in a jar with a secure lid. Add vinegar, water and seasonings. After securing the lid, shake vigorously and refrigerate at least 30 minutes before serving with the salmon.