Drain the cashews, discard the soaking liquid, and add them, apple cider vinegar, Dijon mustard, salt, and water to a blender. Start blending on low and then increase to high and blend until completely smooth. If you don’t have a high-speed blender, soak the cashews for up to 4 hours to help soften them. Transfer to a glass container and use as you wish! You can keep this vegan sour cream in the fridge, in a sealed container for up to 5 days or freeze for later