Sift flour, sugar, baking powder, and salt into mixing bowl; make well in dry ingredients. In this order, add: salad oil, egg yolks, water, vanilla, and grated lemon peel. Beat until satin smooth. Combine egg whites and cream of tartar. Beat until Very Stiff Peaks form. Pour egg-yolk batter in thin stream over entire surface of egg whites, gently cutting and folding just until blended. Bake in ungreased 8 x 8 x 2 or 9 x 9 x 2 inch pan in moderate oven (350 deg. F.) 30 to 35 minutes.

For a 2-layer cake, use the following for filling: Mix sugar, cornstarch, and salt; add egg yolk, water, and lemon juice; cook in double boiler until thick, stirring occasionally.

Remove from heat and mix in lemon peel and butter. Cover surface of pudding with plastic wrap and refrigerate until chilled through. Spread between layers of lemon chiffon cake and drizzle top with glaze. Keep leftovers in fridge.

Glaze: Combine 1 C. powdered sugar and the juice of one large lemon in a microwave container. Microwave 1 1/2 minutes on high. Allow to stand 3-4 minutes.

Pour glaze over cake while the cake is still hot from the oven. (If using just the glaze, cake need not be refrigerated.)