Step 1

Pour 1 cup of unsweetened, unflavored soy milk into a bowl or jar. Remove one tablespoon of the milk.

Step 2

Add 1 tablespoon cider vinegar. Whisk to combine.

Step 3

Let the mixture rest, uncovered, for 10 minutes. It is ready when thickened and lumpy.

Step 4

Keep leftover buttermilk refrigerated for 3-4 days or freeze for up to 3 months.