7 eggs, separated
1½ cup sugar
½ cup orange juice
3 tablespoons lemon juice
1 tablespoon grated lemon zest
1 tablespoon grated orange zest
½ cup matzah cake meal
½ cup potato starch
4 ounces toasted walnuts, ground
¼ teaspoon salt
Preheat the oven to 325 degrees.
In a large mixing bowl, beat the egg yolks and sugar until light in color and texture. Add the orange juice, lemon juice, and grated lemon and orange zest and blend well. Gradually blend in the matzah cake meal, potato starch, and walnuts. Beat the egg whites and salt until stiff enough to hold a peak. Gently fold them into the yolk mixture.
Pour the batter into an ungreased 10-inch tube pan. Bake for 1 hour and 15 minutes, or until the cake springs back to the touch and a toothpick inserted in the cake comes out dry. Remove the cake from the oven immediately invert the pan and let it cool. Loosen the sides and center of the cake with a sharp knife and unmold it onto a cake plate.