Lemon-Vanilla Angel Food Cake
["1 1/2 tsp. cream of tartar", "3 Tbsp. lemon juice", "1 tsp. vanilla extract", "confectioners sugar", "1 1/4 c. granulated sugar or 2 1/2 c. confectioners sugar", "1 c. all-purpose flour or 1 1/4 c. cake flour", "1 1/2 c. egg whites (10 to 12 eggs), room temperature"]
["Preheat oven to 325\u00b0.", "Spray vegetable coating spray lightly onto a tube pan."]
["cream of tartar", "lemon juice", "vanilla extract", "confectioners sugar", "sugar", "flour", "egg whites"]