In a large bowl, combine the milk and vinegar, and let aside to stand for 5 minutes until curdled. Whisk to combine.
In a separate large bowl, mix together the flour, sugar, baking powder, baking soda and salt.
Add an egg, the vanilla and the melted butter to the buttermilk and whisk to combine.
Add the dry ingredients all at once to the wet, and whisk until flour patches disappear. A few lumps are fine, but don't over mix.
Let the batter rest for 5-10 minutes while you heat a pan on the stove.
lightly grease the pan with nonstick spray or butter, and pour about 1/4 cup of batter on the pan. Cook for 2-3 minutes on each side or until golden brown. (Flip the first time once you see bubbles form and the edges of the pancake dry up)