PASSOVER CITRUS SPONGE CAKE
One 10-inch tube cake; 12 to 16 servings
Have all ingredients at room temperature, about 70°F. Preheat the oven to 350°F. Have ready a clean, dry, ungreased 10-inch tube pan.
Whisk together thoroughly in a medium bowl:
- ⅔ cup (80g) matzo meal
- ⅓ cup (55g) potato starch
- ¼ teaspoon salt
Beat in a large bowl or in a stand mixer with the whisk attachment, on high speed until thick and pale yellow, about 2 minutes:
- 9 large egg yolks
- 1 cup (200g) sugar
Beat in:
- Finely grated zest of ½ orange
- Finely grated zest of 1 lemon
- ¼ cup (60g) strained orange juice
- 1 tablespoon (15g) strained lemon juice
Gradually add the matzo mixture to the egg yolk mixture, beating on low speed just until smooth. Using clean beaters, beat in a large bowl on medium speed until soft peaks form:
- 9 large egg whites
- ½ teaspoon cream of tartar
Gradually add, beating on high speed:
- ½ cup (100g) sugar
Beat until the peaks are stiff but not dry. Use a silicone spatula to fold one-quarter of the egg whites into the egg yolk mixture, then fold in the remaining whites. Spoon the batter gently into the tube pan and spread evenly. Bake until the top springs back when lightly pressed and a cake tester inserted into the center comes out clean, 40 to 45 minutes.
Cool and remove from the pan as for Angel Food Cake.