Instructions: To make red wine vinegar, you need two vessels: a 1- to 2-gallon jar and a vinegar crock or sun tea maker with a spigot at the base.

The rest is simple: Pour leftover red wine into the big jar, cover the top with muslin and secure it with a string or rubber band. This will allow air in but keep dust and bugs out. You can set the lid on top, but do not screw it down. Do not fill the jar more than two-thirds full.

You can leave wine sitting in the jar to attract a wild culture of Acetobacter or get a vinegar mother or starter. Grape & Granary sells Store the jar in a dark, cool pantry or cupboard. After five weeks, taste or smell the wine. If it has pleasing hints of vinegar, pour two-thirds of it into the vinegar crock, leaving a third in the jar to start the next batch. This way, the almost-vinegar can mature in the crock without new wine diluting its acidity. (Note: It may take up to two months for the wine to turn.)

Get a cycle going in which you routinely add wine to the large jar but every so often shift two-thirds to the finishing crock.

Before doing this, check the finishing crock and draw off any vinegar that is ready, funneling it into a bottle through a coffee filter. This fermented vinegar will continue to mellow and improve in the bottle.

Troubleshooting: Complete fermentation should take about three months in a dark cupboard kept at about 70 degrees.

If the crock attracts vinegar flies, just filter them out and resecure the muslin. "Theyre just protein," says University of California at Davis researcher Ernie Farinias.

If there is no fermentation with white wine, the sulfite level may be too high. Try diluting it: four parts wine to one part distilled water.

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