Lambic is a style of beer that dates from before the 13th Century. It is only brewed in and around Brussels and the Senne Valley to the south east, usually only between October and May as high temperatures can spoil the distinctive fermentation.
The term itself is a catch-all word for a range of beers including Lambic, Gueuze, Kriek, Framboise, Faro and other specials. The cost of the beer seems high until you find out what goes into making it: the process is significantly different from most other types of beer. These are not known as the champagne of beers for nothing.
First of all, the mash is a combination of 40% unmalted wheat and 60% barley. The mashing process follows the decoction method, in which boiling water is added to the grain in stages. The resulting wort is then boiled for at least three hours with aged hops that have lost their bittering power, but still retain their antiseptic properties.
Once the mash has finished, the wort is pumped up to the top of the brewery into very shallow fermenting tanks. Then special louvres in the top of the brewery are opened which allows wild yeast to flow in and start the fermentation. The two strains that are found in and around Brussels are known as Saccharomyces and Schizosaccharomyces yeasts.
Once the fermentation has started, usually the next morning, the wort is pumped into wooden casks, where it is left to ferment for up to three years. Some is sold off after three to six months. Known as Fos or Fox (young) lambic, this then tends to be very sour, cloudy and golden yellow to orange in colour. It is very difficult to find on sale.
The brewers are not the only people involved in lambic. To make a gueuze, lambics of one, two and three years old are blended together by a specialist blender - rarer even than lambic brewers!
A well-blended gueuze such as Cantillon (brewer and blender) or Drie Fontainen (brewer and blender) is probably one of the most complex, beautiful drinks in the world. Gueuze is sharp, tart and sour, with subtle, complex undertastes. If left for a few years, subtle changes in the flavour leave a gueuze more rounded and not so sharp, but extremely drinkable.
Faro is a blended version of young lambic, sweetened with caramel and candy sugars. It has a rare and unusual sweet and sour taste.
Kriek and Framboise are produced by adding lambic that is between six and twelve months old to a cask of cherries or raspberries respectively, and then left to ferment for months. The fruit is slowly dissolved into the beer and tastes like no fruit drink you have ever had. Blows alcopop into the weeds!
So where can you get these wondrous beers? The best place is, of course, in Belgium. Getting off the Eurostar at Brussels South, the Cantillon brewery and gueuze museum is but 200 yards away and well worth a visit.
Many cafes in Brussels sell lambics. Refer to Stephen D'Arcy's guide or the Tim Webb European guide - both are useful.
If you're after good food and a day drinking lambics, a good place to go is a town south of Brussels called Beersel. All the cafés here sell lambic and there are two lambic brewers in the town: Vandervelden (also known as Oud Beersel) and Drie Fountainen (Three Fountains), which is on the town square, and an excellent place to eat.
You can also find lambics in Ghent, Brugge, Ostend, Antwerp and many other smaller places, though not usually on draught. It can also be pricey, especially Ghent.
In the UK, some CAMRA beer festivals that have a foreign bar may have some lambics, as do a very few specialist beer shops, including the Jug and Firkin (Bacchanalia) on Mill Road in Cambridge.
Not everyone will like the proper, sour lambics, and a lot of Belgian breweries market sweet industrial fruit beers, which from a personal point of view are nowhere as good as the real thing.