Soak raw cashew nuts overnight for at least for 6 hours. Rinse thoroughly under running water.
Combine all ingredients in a blender and blend at high speed until creamy and well-whipped. Do a taste and texture check; add an additional tablespoon of lemon juice if you want it to be more sour, a tablespoon or two of water if you find the consistency to be too dense for your liking*.
Transfer your sour cream to an airtight jar. Keep in the fridge for up to 4 days.
Notes
*keep in mind that vegan sour cream will become thicker in the fridge.