Zucchini and Walnut Cake

1 1/2 c Walnut pieces
2 med Zucchini, unpeeled, ends trimmed
1/4 c Cornstarch
1/4 c Brown rice flour
1 tsp Baking powder
1 pinch Salt
3 large Eggs
3/4 c Sugar
2 tb Diced candied lemon peel, finely minced
Powdered sugar

Preheat oven to 350F. Butter the sides of an 8 x 2-inch cake pan, line the base with a circle of baking parchment and butter the parchment. Using a nut mill, grind walnuts to flour and set aside. Using the same nut mill, grind zucchini into fine shreds. There should be 1 cup, firmly packed, or 6 ounces. Place in a sieve and press out the liquid. Combine cornstarch, rice flour, baking powder and salt; set aside. Beat eggs with sugar until lemon-colored and very thick. A lifted beater should leave a slowly dissolving trail of batter. Using a large rubber spatula, lightly fold in grated walnuts and minced lemon peel, as though mixing a souffle. Fluff up zucchini shreds and fold in. Sift cornstarch-flour mixture over batter and quickly fold in, retaining as much volume as possible. Pour into prepared pan (the batter will be loose) and bake for 40 minutes, until a tester comes out dry. Let cool in pan for 10 minutes before unmolding onto a rack. Peel off paper, reverse onto rack right side up, and let cool completely. Dust with powdered sugar before serving.