But be warned. Not all vinegars labelled 'balsamic' are the real thing. In fact, most are decidedly not even though the label may insist they are. There are three things to look for on the label; either this; 'Aceto Balsamico Tradizionale di Modena' or this; 'Aceto Balsamico Tradizionale de Reggio Emilia', plus the fermenting age which should be at least 12 years for the very best results.

With the true Modena or Reggio Emilia brands you can tell the age from the label. Both use gold labels for balsamic that has aged for 25 years or more, and you will pay accordingly.

Modena brands use red and silver labels to indicate aging of 12 and 18 years respectively, while Emillio Regio's only other label is white, indicating an age of at least 12 years. They are expensive because the best vinegars will have gone through a seven stage fermenting process, starting with a white grape 'must' that is boiled until reduce by half. This must is then transferred over a period of time to a succession of barrels made from different types of wood. With each fermentation a little more of the liquid is lost, a process that is referred to as 'the angels' share'.

Don't be fooled by the words 'Aceto Balsamico di Modena'. These are meaningless and appear on bottles which are little more than ordinary wine vinegar with some coloring added. Many of them originate from areas far removed from Modena itself.

Most supermarket varieties are of this type and while they can be used in place of ordinary vinegar, they are not a suitable substitute for the real thing. You would not, for example, want to put them on strawberries. At least, not if you were then going to serve the strawberries to unsuspecting guests.

The best place by far to buy a true balsamic is an Italian deli where the owner will be more than happy to explain to you the merits of each one he stocks, giving you some idea why you need a second mortgage to buy a bottle. Well, almost. Don't be put off by the seemingly high price. The investment is more than worth it for serious cooks and one bottle will last you a surprisingly long time.

You won't use it as a marinade all that often and when you do, one tablespoonful is usually enough. You are much more likely to experiment with salad dressings to start with, and for those your measurements will be in teaspoons.

If you don't have a local deli, the food hall of a department store is your next best bet or, failing even that, talk to your friendly grocer and see if you can arrange for a special order. I've heard of one group of keen cooks living outback who clubbed together to buy a case, which they replenish on a quarterly basis.

However you make your purchase, work out which balsamic vinegar is the best you can afford and then add $20. This is one occasion when you will truly find that it is money well spent.