Orange Chiffon Cake II

2 c sifted all-purpose flour
1 1/2 c sugar
3 tsp baking powder
1 tsp salt
1/2 tasteless vegetable oil
7 large eggs, separated
finely grated rind of 2 lemons
finely grated rind of 3 oranges
3/4 c orange juice
1/2 tsp cream of tartar
powdered sugar (optional)

1. In a large mixing bowl, sift together the flour, sugar, baking powder, and salt. Make a wide well in the middle of the dry ingredients. Add in the following order, without mixing: oil, egg yolks, lemon and orange rinds, orange juice. With a large wire whisk, beat until smooth. Set aside.

2. In a large mixer bowl, beat the egg whites with the cream of tartar until they hold a stiff peak. Then beat 1 minute more. Do not beat until dry. In 3 additions, fold about 3/4 of the yolk mixture into the whites. Then fold the whites into the remaining yolk mixture, handling no more than necessary.

3. Gently pour batter into a 10 x 4 tube pan (must be a 2-piece pan, NOT non-stick). Bake at 325, on a rack 1/3 up from bottom of oven, for 55 minutes. Then increase temperature to 350 and bake for 10 to 15 minutes more, until the top springs back when lightly pressed with a fingertip. Immediately hang the pan upside down over a funnel or narrow bottle neck. Allow to cool completely. If freezing the cake, freeze it in the pan.

4. To remove the cake from the pan, use a thin sharp knife to cut all the way around the sides of the cake and around the tube. Remove the sides of the pan, then cut the bottom of the cake loose from the pan. Invert the cake onto a plate, leaving it upside down. Sprinkle with powdered sugar through a sieve, if desired.