Combine flour and 1/3 cup sugar; set aside. Beat egg yolks till thick and lemon-colored, about 5 minutes. Add orange peel and juice; beat till very thick. Gradually add 2/3 cup sugar ans salt, beating constantly. Sift flour mixture over yolk mixture, a little at a time, folding carefully just till blended.

Wash beaters. Beat egg whites and cream of tartar till soft peaks form. Gradually add 1/2 cup sugar, beating till stiff peaks form. Fold yolk mixture into whites. Turn into Ungreased 10-inch tube pan. Bake at 325 degrees till cake springs back and leaves no imprint when gently touched, about 55 minutes. Invert cake in pan to cool. Split cake into 3 layers. Whip cream. Stack cake layers, topping each with 1/3 of the whipped cream and sliced strawberries. Trim top with whole berries, if desired.