I had the same question not long ago, this is the way to go.
If you have regular cow’s milk (I like to use 1% milk) and white vinegar, you can easily make the buttermilk yourself.
To make one cup of buttermilk, place one cup of milk in a dish (use a liquid measuring cup to allow for easy pouring afterwards). Add one tablespoon of vinegar, and stir. Allow the milk to sit for about five minutes. Then, use immediately, or place in the refrigerator until ready to use. If you do not have any vinegar, you can use lemon juice in place of the vinegar.
