Passover Sponge Cake - cooking recipe

Ingredients

8 egg yolks
1 cup white sugar
1 tablespoon orange zest
3/4 cup matzo cake meal
1/4 cup potato starch
8 egg whites
1/2 cup white sugar
1 1/2 tablespoons fresh orange juice

Preparation

Preheat oven to 325 degrees F (165 degrees C). Cut parchment paper to line the bottom of a 10 inch tube pan. Do not grease the pan.
In a medium bowl, whip egg yolks until light. Gradually add 1 cup sugar and orange zest; continue whipping until thick and pale, about 7 minutes. Sift together the matzo cake meal and potato starch; set aside. In a large glass or metal mixing bowl, beat egg whites until foamy. Gradually add remaining 1/2 cup sugar, continuing to beat until whites form stiff peaks. Fold the dry ingredients into the yolk mixture alternately with the juice. Fold 1/3 of the whites into the batter, then quickly fold in remaining whites until no streaks remain. Spread evenly into the prepared pan.
Bake for 1 hour and 10 minutes in the preheated oven, until cake springs back to the touch. Invert onto a wire rack to cool. Run a knife around the sides of the cake before removing from the pan.