Red wine vinegar is vinegar made from red wine, as you might imagine from the name. The quality of this vinegar can vary widely, depending on the quality of the starting ingredients, how it was handled, and how long the vinegar was allowed to age. Some red wine vinegars are quite costly, reflecting their extremely high quality, while cheaper vinegars tend to have a more raw, aggressive flavor.

To make red wine vinegar, producers allow red wine to ferment until it goes sour, producing acetic acid. A variety of other acids are often produced during the fermentation process, and the acid percentage varies, depending on how long the vinegar is allowed to ferment. Once fermentation is completed, the vinegar can be strained and bottled, or allowed to age.

Aging is usually accomplished in wooden barrels, and the longer the vinegar ages, the more mellow the flavor becomes. Red wine vinegar can be aged for up to two years before bottling, bringing out the natural layers of the flavor and allowing the aggressive tang to diminish somewhat. Typically, even after purification and straining, a small amount of sediment will remain on the bottom of the bottle.

High-quality red wine vinegar can be used in salad dressings, sauces, and so forth. It may also be cooked in reductions to make sauces which will turn sweet with a faint tangy bite. More sour red wine vinegar can be used for pickling, in slow-cooking processes, and to deglaze pans, when the flavor will be diluted by a variety of other flavors. In marinades, red wine vinegar will help to break down the meat, ensuring that the flavor of the marinade penetrates, although if the marinade is left on too long, the meat may become mushy.

Vinegar can be used in some surprising applications. For example, a red wine vinegar reduction sauce can be drizzled over vanilla ice cream and figs to create a very complex, interesting dessert. A dash of red wine vinegar in a sauce can up the acidity, making the flavor more interesting. Some high quality vinegars made with specialized wines, rather than generic red blends, can also develop some very intriguing flavors which are well worth experimenting with; to test red wine vinegar, dip a small piece of plain bread into the vinegar and eat it. The bread will distribute the flavor and cut the acid slightly so that you can focus on the flavor without being overwhelmed by the tang.