Move oven rack to lowest position and pre-heat to 375°.

½ cup cocoa
¾ cup boiling water
1-3/4 cups cake flour
1-3/4 cups sugar
1-1/2 teaspoons baking soda
1 teaspoon salt
½ cup vegetable oil
2 eggs, separated
2 teaspoons vanilla
½ teaspoon cream of tarter

Stir cocoa and boiling water until smooth. Cool 20 minutes.

Mix flour, sugar, baking soda and salt in a bowl. Make a well and add IN ORDER: oil, egg yolks, cocoa mixture and vanilla. Beat with a spoon until smooth.

Beat egg whites and cream of tarter in a large bowl on high speed until stiff peaks form. Gradually pour egg yolk mixture over egg white mixture, gently folding with rubber spatula just until blended. Pour into an ungreased 10" tube (angel food) pan.

Bake until top springs back when touched lightly, 60 to 65 minutes. Immediately invert on a heatproof funnel or bottle until cake is completely cool.

Removed cake from pan, place on a cake plate and apply your favorite icing or glaze, as desired, or sprinkle with sifted powdered sugar.