Chinese Sponge Cake (Gai Don Go)

1 1/2 cups cake flour, sifted
9 eggs, separated
1/2 teaspoon cream of tartar
1/2 teaspoon baking powder
1 cup sugar
1/2 cup water
1/4 cup vegetable oil
1 teaspoon vanilla extract

Beat egg whites until slightly foamy. Add 1/2 teaspoon cream of tartar. Beat again until stiff.

Sift together flour, baking powder and sugar. Add to egg yolks; add water, oil and vanilla extract and beat until creamy. Pour the mixture over egg whites gently and fold until well-blended.

If using a 9 x 13-inch pan, bake at 350 degrees F for about 20 minutes. If using a tube pan, bake 35-40 minutes, inverting tube pan upside down while cooling.

Serve with fruit topping and whipped cream.