"Buttermilk is a buttery, slightly thickened milk that makes for wonderful biscuits, pancakes, muffins, cupcakes and other various breads.
To my knowledge, there is no vegan buttermilk sold commercially. Luckily though, it is super easy to make your own. Say you need 1 cup “buttermilk”; here’s how you would make it:
Place 1 tablespoon lemon juice, lime juice, apple cider vinegar, or white vinegar in a measuring cup.
Add enough non-dairy milk (of your choosing) until it reaches the 1-cup line; stir with a fork or whisk.
Allow mixture to rest for 5-10 minutes."
See more @ VeganFoodAddict