Heat oven to 450°F. Line 15x10x1-inch baking pan with foil; generously spray foil with nonstick cooking spray.
In small bowl, combine sour cream, onion salt and lemon peel; mix well. Rinse cod pieces; blot dry with paper towels. Place fish in sprayed foil-lined pan, tucking under any thin portions so fish is of even thickness. Spread sour cream mixture evenly over fish.
Bake at 450°F. for 15 minutes or until fish is almost done.
Meanwhile, place bread pieces in blender container; blend until about 1/2 cup soft crumbs form. In small bowl, toss crumbs with margarine, dill and paprika.
Sprinkle crumb mixture over fish; bake an additional 3 to 7 minutes or until crumbs are toasted and center of fish flakes easily with fork.