2 c. unsifted all-purpose flour
1 1/2 c. granulated sugar
1 tbsp. baking powder
5 lg. egg yolks
1 c. fresh orange juice
6 tbsp. grated orange peel
1 tsp. vanilla extract
1 c. egg whites (7 to 8), room temperature
1/2 tsp. cream of tartar
3 c. confectioners' sugar
2 tbsp. butter, melted

Preheat oven to 325 degrees. In medium bowl, combine flour, granulated sugar, baking powder, and 1 teaspoon salt. Make a well in center of mixture; add 1/2 cup salad oil, the egg yolks, 3/4 cup orange juice, 3 tablespoons orange peel, and the vanilla. Beat until smooth; set aside.

In large bowl of electric mixer, at high speed, beat egg whites with cream of tartar until stiff. Pour flour mixture gradually over egg whites, folding with rubber spatula until no white streaks remain. Pour into ungreased 10 inch tube pan; bake until wooden pick inserted in center of cake comes out clean, about 1 hour.

Invert cake in pan over neck of a bottle; let stand until completely cold, about 1 1/2 hours. Carefully invert onto serving plate; remove pan. Meanwhile, in medium bowl, blend confectioners' sugar with melted butter and remaining orange juice and grated orange peel. Drizzle over cake; garnish with fresh orange slices, if desired. Makes 12 servings.