Soak the cashews in boiling water for about 10 - 15 minutes. Then drain and add then to a HIGH SPEED blender (like a Vitamix)
Add the Water or Plant Milk (Water will give a thinner consistency, Plant Milk a thicker, richer one, so choose based on what you'd like.) The more liquid you add the thinner the cream will be. I'd suggest starting with 1/2 cup and adding more as you see fit. Blend until smooth in a HIGH SPEED BLENDER (this is necessary unfortunately to avoid a chunky cream)
Add any lemon juice, vinegar or salt that you see fit.
Store in the fridge and use within 1 week.