Cover the raw cashews in a sealed jar filled with water, and let sit for at least 4 hours to soften. Alternatively you can boil them for a few minutes, though I have not tried this method.
Drain the cashews, then place them in a blender or food processor with the remaining ingredients. Blend on high for 45-60 seconds, until a creamy sauce is formed.
Store in an airtight container in the fridge for up to 7 days.