Instructions

1. Mix the milk with the apple cider vinegar and let it sit for 5-10 minutes until it slightly curdles.
   
2. Meanwhile, sift the flour into a large bowl. Add the sugar, salt, and baking soda. Mix well.
   
3. Melt the butter over very low heat.
   
4. Separate the egg yolk from the white and beat the egg white to soft peaks.
   
5. Once the milk has rested, add the egg yolk, melted butter, and vanilla extract, stirring to combine.
   
6. Gradually pour this mixture into the flour, whisking until you get a smooth batter. Don’t overmix: a few small lumps are fine.
   
7. Gently fold the beaten egg white into the batter.
   
8. If needed, lightly grease your waffle iron with sunflower oil. Pour in the batter using a spoon or a small ladle and cook until the waffles are golden. The amount of batter and cooking time will depend on the size and model of your waffle iron.