Preheat waffle iron.
Mix dry ingredients (flour through salt) in a medium bowl.
In a separate bowl, mix milk, oil, and egg yolk and set aside. Whisk egg white in a small dish until light and frothy.
Add wet ingredients to dry (keeping egg white separate) and mix until batter is smooth. Gently fold in egg white and stir until well combined.
Grease waffle iron with oil or cooking spray. Add ½ cup batter per waffle, cooking until brown and crispy. Serve immediately.