Sponge Cake

INGREDIENTS:

8 egg yolks
1 cup white sugar
1 tablespoon orange zest
¾ cup matzo cake meal
¼ cup potato starch
8 egg whites
½ cup white sugar
1 ½ tablespoons fresh orange juice

DIRECTIONS:

Preheat the oven to 325 degrees F (165 degrees C). Grease and line the bottom of a 10-inch tube pan with parchment paper.
Whisk egg yolks in a medium bowl until lighter in color. Gradually add 1 cup sugar and orange zest; continue whisking until thick and pale, about 7 minutes.
Sift matzo cake meal and potato starch together; set aside.
Beat egg whites in a large glass or metal mixing bowl until foamy. Gradually add remaining 1/2 cup sugar, continuing to beat until whites form stiff peaks. Fold matzo mixture into yolk mixture alternately with orange 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 …