Pistachios give this flavored kefir an extra-thick texture. The drink can also be made with 1 cup store-bought plain kefir.
Pour milk into 16-oz. glass jar, and stir in kefir grains. Cover jar with several layers of cheesecloth or paper towels, and secure with rubber band.
Store jar at room temperature out of direct sunlight, and allow kefir to ferment 24 hours, or until thickened. (Healthy kefir grains will thicken milk in 24 hours, though this process may take as few as 12 hours in warmer temperatures, or as long as 48 hours in cooler temperatures.) Check kefir periodically to gauge thickness.
When mixture reaches desired thickness, strain kefir into glass, stirring gently until only kefir grains remain in strainer. (To keep kefir grains viable, stir into new batch of milk within 48 hours.)
Blend prepared kefir, cherries, pistachios, honey, and cardamom in blender until smooth and creamy.