Anthony Barton of the eponymous chateaus in Bordeaux once remarked that 'wine is the brief interlude between grape juice and vinegar'. It's true; a wine that's been naturally fermented and without additives will become vinegar upon exposure to air, a fact long known to wine-makers. Like many great accidental discoveries, vinegar was quickly recognised as immensely useful and was used as an acid from the earliest recorded history. As an adjunct to gastronomy its history is also long. The most prestigious vinegar of all comes from Modena in Italy, where they make the internationally renowned 'balsamic' vinegar. The earliest reference to it is from 1046, when a barrel of it was given to King Henry II of Franconia.

A true balsamic vinegar - bottled with the word 'tradizionale' on the label - begins life as very ripe and sweet Trebbiano grapes. These are pressed and the resulting juice, or must, is boiled until it has reduced in volume by 30%. The cooked must then goes through a very slow process of acetification - lasting up to a maximum of 25 years for a 'tradizionale extra vecchio' - where the vinegar matures in barrels of different woods. Rather like the 'solera system of Jerez, the balsamic moves from barrel to barrel, taking on the flavours imparted by the woods. The most commonly used are oak, chestnut, cherry wood, ash, and mulberry. Each 'tradizionale' balsamic vinegar undergoes 90 tests at the consortium, is given a number and is then recorded in a large book.

That its popularity has grown over the past decade is perhaps something of an understatement. The words 'balsamic reduction' appear on restaurant menus with regularity, supermarket shelves carry it and celebrity chefs use it on TV. But this hugely increased demand could simply not be met by the traditional methods, nor was the price of the real thing attractive - up to €2,000 a litre. Therefore the non-traditional, or commercial, balsamic made its appearance to satisfy market demand. This too is classified, from one to four vine leaves, which can be found on the label. 'One leaf' is the lightest and cheapest, useful for salads and everyday use, 'four leaves' is the closest to the 'tadizionale' and will cost accordingly more.

As a condiment it's very verstatile; you can use it on grilled meats, salads, on Parmesan shavings and even on fruit. When you use it cooking, use it at the end of the cooking process so that the flavours won't evaporate. Last summer in Italy I was handed a bowl of strawberries that had flavoured with balsamic vinegar, and it was a dish that left a lasting impression on me, truly a combination made in heaven. If you want to try it I suggest you put some balsamic in a sprayer and spray the fruit, rather than pouring it on.

Bottle of the Week

Balsamic Vinegar from Mazzetti of Modena, 10 year-old.

This has a three-vine classification, round and smooth in flavour with a pleasingly dark colour. A good balance of sweet and sour, it's cheap enough to use for sauces and salads in generous quantities.

Available Superquinn and selected delicatessens, RRP €7.99 500ml.