Simple Chiffon Cake

1. Preheat oven to 250 degrees F. 2. Sift cake flour and baking powder in a medium bowl. Set aside. 3. In a separate bowl, beat egg-yolk, sugar, emulsifier, salt and vanilla extract with high-speed mixer until light and fluffy. 4. Fold in cake mixture into the egg-yolks mixture. whisk well. 5. Add in milk into the flour, egg-yolk mixture. mix well. 6. Beat egg whites and cream of tartar with a mixer on high speed until foamy. Then, gradually add sugar little by little while beating. Beat until stiff, glossy peaks form, about 5 minutes. 7. Gently, fold in egg-white mixture into the flour, egg-yolk mixture with a rubber spatula just until well mix. 8. Then, add cooking oil and gently mix the batter. 8. Transfer batter to tube pan. Bake until top of cake springs back when touched, 50 to 55 minutes. Let cool upside down (over a bottle or on tube-pan feet) for at least 1 hour.