In a small bowl combine the milk and vinegar. Set aside for 10 minutes to "sour."
In a larger bowl, combine flour, sugar, baking powder, baking soda and salt.
Add the vanilla, egg, and melted butter into the small bowl with the soured milk. Whisk together. Pour into the dry ingredients and whisk until most of the lumps are gone, but DO NOT OVER BEAT!
The batter will be super thick. Let it sit for 10 minutes. After 10 minutes, you will see bubbles in the batter. Don't stir again.
Gently dip a laddle into the batter and put on a buttered frying pan. Cook until bubbles appear on the surface of the pancake and then flip with a spatula and brown the other side.