The Ferrari of vinegars? That would be balsamic vinegar, made exclusively in northern Italy in the provinces of Reggio and Modena (the latter also famous for producing Ferraris and tenor Luciano Pavarotti). The finest balsamics -- artisan-made or "tradizionale" as opposed to commercially produced -- have more in common with fine liqueur, port or sherry than with other vinegars, and over the centuries have been served in thimble-sized goblets for toasts on extraordinary occasions. A hard-to-come-by bottle of the nectar can now cost more than $100, and little is available to the public.
Unlike wine, balsamic vinegar was traditionally made by women. Commercial production of balsamic vinegar began only about 35 years ago; a family's vinegar is handed down from generation to generation, sometimes as part of a bride's dowry.
Made from a sweet syrup of trebbiano grape juice, balsamics are aged for 12 to 100 years in a series of smaller and smaller casks made of different woods, such as acacia, oak, juniper and chestnut. Prized for its rich, complex, sweet-sour flavor and its healing properties, the soothing medicinal balm -- or "balsam" -- was said to cure everything up to and including the plague.
Most of what we see in the United States is commercially produced, made in factories at about 1/13th of the cost of the artisan-made; the difference is roughly analogous to that between cultured pearls and deep-sea pearls. To ensure authenticity and avoid confusion with lesser-quality brands made other parts of Italy or bottled in the United States, look for the codes API MO (for Modena) and API RE (for Reggio).
Balsamic vinegar will keep for several years, securely capped and stored in a cool dark place. Transfer to a smaller bottle as it is used, to ensure less exposure to oxygen.