Buttermilk is a versatile ingredient in the kitchen, adding tang to everything from salad dressing to home-baked bread to fried chicken. Making your own is as easy as combining just two ingredients, then letting nature take its course. You’ll need a small amount of store-bought cultured buttermilk (make sure it’s cultured), milk and a lidded container.
Start with Cultured Buttermilk
Pour about 1/2 cup of the cultured buttermilk into the bottom of the container. Make sure the container is large enough to accommodate the amount of dairy you’re working with.
Stir to Combine
Pour in 1 quart of milk. Whole milk is ideal, but 1 percent is perfectly fine. Stir to combine the milk and buttermilk thoroughly.
Leave at Room Temperature
Place the lid on your container. (A standard Mason jar will do, or use any non-reactive container with a lid.) Leave it out on the counter at ambient room temperature.
Wait 12 to 24 Hours
After 12 to 24 hours, the mixture will thicken. The longer you leave it out, the thicker and tangier the buttermilk will be. Depending on how warm your kitchen is, it may also take longer. Once the buttermilk has reached the texture and flavor you desire, store it in the refrigerator for up to a month.
Use your buttermilk as you would store-bought buttermilk, like in a homemade buttermilk ranch dressing. When you are down about half a cup, you may repeat the process by adding your homemade buttermilk to fresh milk.