If you are out of buttermilk, don't worry! You can use regular milk in place of the buttermilk. Add 1 tablespoon of white vinegar or lemon juice to a liquid measuring cup then fill it to the one-cup line with milk (do not use ultra-pasteurized). Let it sit for five minutes before adding to the other ingredients in the recipe. The mixture will lightly curdle, creating a buttermilk substitute. It is perfect when you don't have buttermilk and it doesn't make sense to buy a whole container.