Fill a sanitized 1-gallon jar with juice, leaving about 2 inches of headspace.

If using wine yeast, hydrate the yeast by sprinkling it over the warm water in a cup. Stir gently, let sit for 20 minutes, then add hydrated yeast liquid to the jar and stir well.

Cover jar with a piece of unbleached cotton (butter muslin or tightly woven cheesecloth), or a basket-style paper coffee filter. Secure the cloth or filter with a string or rubber band, or the screw on the jar ring. This is to keep out fruit flies.

Place in an environment where the temperature is between 55 and 65 degrees F.

At 7 to 10 days, add vinegar starter. Replace cover on jar. Store on your counter or in another spot that is 75 to 86 degrees F. Over the next few weeks, a mother will likely develop. It is a cellulose film that grows on top.

Check the vinegar in a month, when you should have nice acidity. However, it may take an additional month or two to fully develop, especially if your environment is cooler.

Bottle finished vinegar in an airtight bottle. Save the mother for another batch or share it with a friend. Use vinegar immediately, or age to allow it to mellow and further develop flavor.