To a large glass container (1 quart/liter size mason jars work well), soak the grains in enough water to fully cover. Let this sit at room temperature away from direct sunlight for 6 to 8 hours.
After soaking, drain the water. Rinse the grains a couple times.
Drain the water again, cover the top of the jar with a cheesecloth and secure it with a rubber band or the ring of the jar lid.
Let the grains sit at room temperature until sprouts form, about 1 to 2 days. Keep the grains from drying out by rinsing and draining them 2 to 4 times a day.
When the grains have begun to sprout, rinse them one more time and drain.
Fill the jar with fresh water. Let this ferment for 2 to 3 days.
As the mixture ferments, gas bubbles will form and the water will become cloudy. There may be some white film on top; this is normal. Taste it to see that it's ready. The taste will be tangy with a hint of lemon. It should be fresh and pleasant tasting.
Strain the liquid into a clean jar and it's ready to use in your own vegan cultured cheese.
You can add more water to the grains to make a second batch of rejuvelac. It will only take a day.
