Homemade Wine Vinegar
Make your own wine vinegar, using leftover wine, by following this easy recipe:
1 quart of wine
1 teaspoon apple cider vinegar
Combine, place in sun, lightly covered with plastic wrap. Let rest for 2-3 days.
Always use a good wine – never use one you wouldn't drink.
from Daniel Rogov, author of Rogov's Guide to Kosher Wines 2010, 2011