In a medium glass or ceramic bowl with a lid, combine the cashews with the water, and pour in the contents of the probiotic capsule (discarding the empty capsule shell) or the probiotic powder. Stir the ingredients together until combined.
Attach the lid, and let sit for eight to twenty-four hours, depending on how tangy you like your yogurt.
Puree the ingredients in a blender until smooth, then return the yogurt to the bowl. Garnish with pomegranate arils or cherries if desired, and enjoy immediately, or refrigerate for up to four days.