Fit a 2-quart souffle dish with a greased and sugared foil collar; set aside. In a saucepan melt butter or margarine. Stir in flour and salt. Add milk; cook and stir until thick and bubbly. Mixture will be very thick. Remove from heat. Stir in orange peel and orange juice. Mix well. Beat egg yolks about 5 minutes or until thick and lemon colored. Gradually blend orange mixture into beaten egg yolks. Wash beaters thoroughly.l In a large mixer bowl beat egg whites to soft peaks. Gradually add sugar, beating to stiff peaks. Fold orange mixture into egg whites. Turn into ungreased souffle dish. Bake at 325 for 60 to 65 minutes or until a knife inserted near center comes out clean. Serve immediately with Orange Sauce.