Feather Sponge Cake - cooking recipe

Ingredients

6 egg yolks
1/2 c. cold water
1 1/2 c. sugar
1/2 tsp. vanilla extract
1/2 tsp. orange or lemon extract
1 1/2 c. cake flour
1/4 tsp. salt
6 egg whites
3/4 tsp. cream of tartar

Preparation

Beat egg yolks until thick and lemon-colored.
Add water and continue beating until very thick.
Gradually add sugar, then extracts.
Fold in flour sifted with salt, a little at a time. Beat egg whites until foamy; add cream of tartar and beat until they form moist, glossy peaks.
Fold into egg yolk mixture.
Bake in 10-inch ungreased angel-cake pan in slow oven (325\u00b0) for 1 hour.
Invert pan to cool.