In a large measuring cup, measure milk and add vinegar. Stir slightly and set aside to allow the mixture to "sour" for 10 minutes.
In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
Make a well in the center and add milk mixture, eggs, melted butter and vanilla. Add mix-ins now. Stir all ingredients together just until there are no visible flour pockets remaining. Please note: You do not want to over mix this batter - it should be a little lumpy. If the batter is completely smooth and runny, you will have flat pancakes - which taste equally delicious but flat. Set batter aside to rest.
Turn griddle on medium low heat and add butter or non-stick cooking spray. Pour about 2 tbs-¼ cup of batter for each pancake. Once you see a few bubbles on top and underneath is golden brown, flip and cook the other side - about 2 minutes on each side. Continue the cooking process for the rest of the batter.
Serve pancakes immediately with some butter, maple syrup, whipped cream or whatever your little heart desires!