Sift flour with 1 c. sugar, baking powder and salt
Measure into mixing bowl egg yolks, oil, water, orange juice and peel. Add sifted dry ingredients. Beat until smooth, about ½ minute at low speed of mixer, or 75 strokes by hand.
Add cream of tartar to egg whites. Beat until soft peaks form. Gradually add remaining ½ c. sugar, beating until mixture stan