Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   1 1/2  pounds        catfish fillets
   1      tablespoon    lemon juice
                        egg whites
   2      tablespoons   sour cream
   1      tablespoon    grated onion
   1      clove         garlic
     1/4  teaspoon      dry mustard
     1/4  teaspoon      white pepper
   2      tablespoons   butter or margarine
   2      tablespoons   flour
   1      cup           milk
   4      teaspoons     prepared horseradish

Preparation:

Arrange fish on baking pan sprayed with nonstick cooking spray. Sprinkle with lemon juice. In small bowl beat egg whites until soft peaks form. Fold in sour cream, onion, garlic, mustard and 1/8 teaspoon white pepper. Spoon some of mixture on top of each fillet. Bake at 375F for 20 minutes or until fish is opaque or skewer glides easily through flesh. Meanwhile in small saucepan melt butter. Blend in flour until smooth. Stir in milk, horseradish and remaining 1/8 teaspoon white pepper. Cook and stir over medium heat until mixture is bubbly and slightly thickened. Serve over fish.