1. Preheat the oven to hot (400°). Line a 15 x 10 x 1-inch jelly-roll pan with aluminum foil.
2. Beat the whole egg and the water together in a small pie plate. Pour the bread crumbs onto a piece of wax paper. Dip the fish first into the egg mixture; then coat the fish with the bread crumbs on both sides. Place the fish on the prepared pan.
3. Bake the fish in the preheated hot oven (400°) for 5 to 7 minutes or until the fish is white and firm to the touch.
4. Prepare the Creamy Horseradish-Dill Sauce: Stir together the sour cream dressing, horseradish and dill in a small bowl. Beat the egg white in a second small bowl until soft peaks form; fold the whites into the dressing mixture.