Pineapple-Nut Passover Sponge Cake

Ingredients

 * ¾ cup potato starch
 * ¼ cup cake meal
 * ½ tsp each ginger and nutmeg
 * ¼ tsp salt
 * 10 large eggs (use 4 yolks - 10 whites)
 * ⅔ cup superfine white sugar
 * 1½ tsp each minced lemon and orange
 * zest from navel orange
 * 3 tbsp frozen pineapple concentrate
 * ½ cup blanched almonds
 * 1 tbsp 10x sugar

Directions

 * 1) Preheat oven to 325 °F.
 * 2) Line the bottom of a 9" tube pan with a doughnut shaped piece of wax paper, notching around the center circle every inch.
 * 3) Do not grease pan.
 * 4) Sift first 4 ingredients into a bowl.
 * 5) Set aside.
 * 6) Separate eggs, dropping 4 yolks into one mixing machine bowl and 10 whites into another.
 * 7) Using whisk attachment, beat egg whites on medium high speed until foamy.
 * 8) Turn speed up to high.
 * 9) Sprinkle in half the sugar and beat until stiff and glossy.
 * 10) Set bowl with yolks on machine.
 * 11) Beat until light.
 * 12) Sprinkle in remaining sugar, zests and concentrate.
 * 13) Beat on high speed until well blended.
 * 14) Using a wooden spoon, stir about ½ cup of beaten whites into yolks.
 * 15) Then pour all of yolk mixture over beaten egg whites.
 * 16) Fold in by hand in 12 sweeping strokes.
 * 17) Sift dry ingredients again over all and continue folding for another 12 strokes.
 * 18) Sprinkle and fold in nuts (another 12 strokes would suffice).
 * 19) Spoon into prepared pan, smoothing out top.
 * 20) Run a blunt knife around sides to dispel any air bubbles.
 * 21) Bake in center section of oven for 55 minutes. Top should be lightly browned and toothpick, when inserted, should come out clean.
 * 22) Remove from oven and invert tube onto a 3-cup mason jar with a 1½" neck, or any convenient holder that will fit the tube.
 * 23) Cool for 1½ hrs.
 * 24) Gently unmold.
 * 25) Peel off wax paper.
 * 26) When completely cooled, sift confectioner's sugar over.
 * 27) Cut with sharp serrated knife, or pull apart servings with fork.