1 cup raw cashews, soaked overnight OR 1 (12.3 oz) package silken tofu
1 tablespoon unsweetened plain nondairy yogurt
Purée cashews or silken tofu with yogurt until completely smooth. If using cashews, you may need to add 1-2 tablespoons of water to achieve a creamy consistency.
Transfer cashew/tofu cream to a clean container. Cover and allow to culture in a warm place (such as on top of the fridge or inside the oven) for 1-3 days. The longer you culture it, the more sour it will become.