In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In a separate bowl, whisk the egg yolks, milk, vegetable oil, and vanilla extract.
Pour the wet ingredients into the dry ingredients and whisk until just combined. Do not overmix.
In a clean bowl, beat the egg whites until stiff peaks form. Gently fold the egg whites into the waffle batter.
Preheat your waffle iron according to the manufacturer's instructions. Lightly grease if necessary.
Pour about 1/2 cup of batter onto the preheated waffle iron and cook until golden brown and crispy, about 3-5 minutes per waffle.
Repeat with the remaining batter. Serve immediately with your favorite toppings.
Notes
For extra crispy waffles, you can place them on a wire rack in a warm oven while you cook the remaining waffles. Consider adding a pinch of cinnamon to the dry ingredients for a hint of spice.