Orange Sponge Cake
["6 egg yolks", "1 Tbsp. grated orange peel", "1/2 c. orange juice", "1 c. sugar", "1/4 tsp. salt", "1 1/3 c. sifted cake flour (Softasilk Cake Flour)", "6 egg whites", "1 tsp. cream of tartar", "1/2 c. sugar"]
["Beat egg yolks until thick and lemon-colored.", "Add orange peel and orange juice.", "Beat until very thick.", "Gradually beat in 1 cup sugar and 1/4 teaspoon salt.", "Fold in flour a little at a time.", "Beat egg whites with the cream of tartar until soft peaks form.", "Gradually add 1/2 cup sugar beating until soft peaks form. Thoroughly fold whites into yolk mixture.", "Bake in ungreased 10-inch tube pan in slow oven (325\u00b0) about 55 minutes or until done.", "Invert pan to cool."]
["egg yolks", "orange juice", "sugar", "salt", "cake flour", "egg whites", "cream of tartar", "sugar"]