This is the only vinegar not made from wine, but from the cooked and concentrated must of the white grapes of the Trebbiano vine. Balsamic vinegar is aged in kegs made of different woods: oak, cherry, chestnut, mulberry and ash, one for each year of maturing. When the new grapes arrive in the fall (autumn) some must from the first year is syphoned into the next barrel, some of this into the third year barrel and so on. The result of this complicated process is a nectar with a well-balanced flavor and a rich velvety-brown color. By law, vinegar that is labeled aceto balsamico tradizionale must be at least ten years old and in fact, it is sometimes 50 years old or more. It is full-bodied, rich vinegar with a dark brown color glinting with gold, and is very aromatic, with a peculiarly delicious flavor all of its own. There also exists a commercial version, called simply aceto balsamico which cannot be sold as tradizionale. It has a similar flavoring but has not been aged for so long. The flavor is sometimes obtained by adding a little caramel to a good-quality white wine vinegar. Balsamic vinegar is produced in the province of Modena in Emilia Romagna, and also, by a slightly different method, in the province of Reggio-Emilia. Up until the 1980's it was almost unknown outside the region, but now it is a popular ingredient in many dishes. Good balsamic vinegar is used to dress strawberries, to sharpen a vanilla ice cream, to flavor consomme, and for special marinades. It seems odd, but aceto balsamic tradizionale also makes an excellent thirst-quenching drink diluted with ice and sweetened with a little sugar.