Matzo cake flour
Beat egg whites until stiff peaks form; set aside. Beat egg yolks and powdered sugar. Sift flour; add to egg yolk mixture. Add vanilla, salt and orange peel, if desired. Stir in walnuts. Fold in egg whites. Spoon into 10" tube pan. Bake @ 350 degrees for 50 minutes. Invert and cool before removing from pan.