**Mix Dry Ingredients:** In one large bowl, whisk flour, cornstarch, sugar, baking powder, and salt.
**Add Wet Ingredients:** Add milk, oil, egg yolks, and vanilla to the same bowl. Whisk until just combined. A few lumps are okay. Do not overmix.
**Whip Egg Whites:** In a separate small bowl, beat the 2 egg whites with a hand mixer until stiff peaks form. This takes 2 minutes.
**Fold Gently:** Gently fold the beaten egg whites into the batter using a spatula. Stop when no white streaks remain. This keeps them fluffy.
**Cook:** Preheat your waffle iron to medium-high. Spray with non-stick spray. Pour 3/4 cup batter and cook 4-5 minutes until golden brown and crisp.