Thaw cod if frozen and pat dry. Arrange fish in prepared baking dish in a single layer and sprinkle with salt and pepper. Combine sour cream, mustard, dill, onion and wine in a small bowl and mix well. Spread sauce evenly over fish and sprinkle with bread crumbs. Bake 15-18 minutes, until fish flakes easily when pressed and top is golden.
Leigh's tip: Substitute 2-3 teaspoons dried dill weed for the fresh dill.