Place cashews in a bowl and cover with a few inches of water. Let soak until soft, 8 hours to overnight.
Drain and rinse cashews; transfer to a high-powered blender. Add 4 tablespoons water, lemon juice, vinegar, and salt. Blend until cashews are finely ground. Scrape down the sides of the blender and add remaining water; blend until very smooth.
Transfer cashew cream to a jar with a tight-fitting lid and store in the refrigerator.