Soak raw cashews overnight in water covered on the countertop for about 8-12 hours. Quick method - soak raw cashews in very hot water for 15 minutes to 1 hour before blending. (the longer they soak the smoother the consistency.)
Drain the soaking water off of the cashews and add them to a blender with 1 cup of filtered water and blend on high for 2 minutes until smooth and creamy.
Notes
Add a little more water for a thinner cream.
Add a little less water for a thicker cream.
For cashew sour cream reduce the blending water to 1/2 cup and add 2 teaspoons of lemon juice.
This recipe yields about 2 cups of vegan heavy cream.