Whisk together flour, cornstarch, baking powder, sugar, and salt in a large bowl.

In another bowl, combine milk, oil, egg yolks, and vanilla.

Beat egg whites separately until stiff peaks form.

Pour wet ingredients into dry ingredients and mix until just combined.

Gently fold in beaten egg whites.

Let batter rest for 10-20 minutes.

Heat waffle iron to highest setting.

Pour batter onto center of hot iron and cook until golden brown.