Place the raw cashews in a large, heatproof bowl and carefully cover them with the 8 cups (1920 ml) of boiling water.
Cover the bowl with a clean kitchen towel and let the cashews soak for 6 to 8 hours, or overnight, to soften completely.
Drain the cashews thoroughly and discard the soaking water.
Transfer the softened cashews to a high-speed blender.
Add ⅓ cup of cold water to the blender.
Blend on high for 3-5 minutes, scraping down the sides as needed, until the mixture is perfectly smooth and thick, resembling the consistency of sour cream.
Add more water, a tablespoon at a time, if needed to reach your desired consistency.
Adjust the amount of blending water to control the thickness. Use less water for a firm, cheese-like consistency and more for a pourable cream sauce.
Add a tablespoon of lemon juice or apple cider vinegar for a tangy flavor, perfect for mimicking sour cream or cream cheese.
