How to Make It
Preheat oven to 350°.
Lightly spoon flour into a dry measuring cup; level with a knife. Combine flour, sugar, baking powder, and salt in a large bowl; stir well. Add rind and next 5 ingredients (through egg yolks); beat at medium speed until smooth. Beat egg whites and cream of tartar until stiff peaks form. Gently stir one-fourth of egg whites into batter; fold in remaining egg whites. Pour mixture into a 10-inch tube pan with removable bottom. Bake at 350° for 25 minutes or until cake springs back when lightly touched. Let cool on rack 5 minutes in pan. Remove from pan; cool completely. Dust with powdered sugar. Serve with berries.