I don’t know about you, but I don’t always keep buttermilk on hand. In fact, I only buy it when I have several recipe to make that require it. Otherwise, I find that it ends up being thrown out before I can use it all. I often use this buttermilk sub recipe instead. It’s so simple, just 2 ingredients (vinegar + milk), that I always have on hand. Not to mention, this is much cheaper than buying buttermilk!
For one cup of buttermilk: Place a tablespoon of vinegar in a liquid measuring cup. Fill milk up to one cup line. Let sit for 5 minutes before using.