Preheat waffle iron.
Sift then measure flour. Add baking powder, salt, and sugar in large bowl.
Combine egg yolks, milk, & cooking oil in a small bowl. Add to dry ingredients. Mix until well blended.
Fold stiffly beaten egg whites into the batter with a spatula.
Pour batter into center on hot waffle iron. Bake until steaming stops.
Lift off carefully with spatula. Serve immediately.