Buttermilk is important because that's what helps make the chicken so tender. If you don't have any on hand, and don't want to wait to make this recipe, you can always make your own using vinegar and milk. 1 cup buttermilk = 1 Tablespoon white vinegar + enough milk to measure 1 cup, OR 1 cup buttermilk = 1 Tablespoon lemon juice + enough milk to measure 1 cup. Let stand 5-10 minutes.