Put the cashews and salt in a blender. Turn on the blender and pour in just enough of the rejuvelac through the cap opening in the lid to process the cashews. (The longer the cashews have soaked, the less liquid will be required for processing. Also note that a high-powered blender can process the cashews with less added liquid.) Process until smooth and creamy, occasionally stopping to scrape down the blender jar and move the mixture toward the blades.

Transfer to a clean glass bowl or container, cover, and let rest at room temperature for 8 to 36 hours, depending on how sharp a flavor you want and the ambient temperature (culturing will proceed more quickly at warmer temperatures). The cheese will thicken as it cultures.

If you will eventually be using the cheese as a base for another recipe, simply cover and store it in the refrigerator for up to 2 weeks. Otherwise, transfer to a glass or nonreactive metal mold and smooth the top. Cover and refrigerate for at least 6 hours, until firm.