Dordogne Chateaux and their Black Gold

January is the month in Europe when most people wish they had flown south with the swallows. The joys of Christmas are past, and one looks forward to the first hints of spring. In the province of Aquitaine, the wine harvest is safely in the cellar, and the maturation process is well under way. But the region continues to provide bounty of a different kind. For those who have The Knowledge, there is black gold to be dug from the leaf-covered earth - black Périgordine truffles, or Tuber Melanosporum, to give them their botanical name. Accompanied by his faithful truffle hound (they are trained from birth to sniff out this elusive treasure) a knowledgeable truffle hunter will spend hours in solitude, searching the earth and mining these gourmet black diamonds.

Truffles grow around the roots of trees such as oak and hazelnut in amongst the grounds of Dordogne chateaux and estates. They are choosy about where they will establish themselves, but the limestone hills and valleys of the Dordogne provide the perfect habitat - a bonus for those owning the beautiful Dordogne chateaux and country houses for which the Dordogne is famous. Their whereabouts tend to be a secret which is closely guarded and often handed down from generation to generation, and with good reason. These rich earthly delicacies sell for up to €1,000 per kilo at the Dordogne's truffle markets at Saint-Alvère, Sarlat-le-Canada, Brantome and Perigueux (in 2007 a white truffle from Piedmont weighing 1.5 kilograms was bought at auction by a Macao casino owner for US$330,000), and are highly prized in the world's best restaurants.

The famed French 18th century gourmand Jean Brillat-Savarin called truffles "the diamond of the kitchen". The season for black truffles runs from November to February and they are best eaten very fresh. Many are shipped off to clients as far afield as China and America. Truffles impart their elusive, subtle flavour to dishes ranging from the humble mashed potato to foie gras or fillet steak. Try a truffle omelette (secret tip: store your truffle with your eggs for a day - it makes all the difference), adding slivers of truffle at the last minute. Or make a cream sauce with pasta and scatter thin wisps of truffle on top. Inspired by a delicious starter at Coté Bastide restaurant in Sainte-Foy-la-Grande, where the chef is a true sorceress with food, my wife shaves a few frilled truffle ruffles, just before serving, on to a bowl of creamy cauliflower soup drizzled with a little truffle oil: a heavenly experience.

So yesterday, I made the pilgrimage to the Marché des Truffes at Saint-Alvère (pictured), accompanied by a retired diplomat who lives in a beautiful Dordogne chartreuse nearby and is a fund of knowledge on fine wines, the region's rich history and all things culinary, including truffles. As the doors of the indoor market opened punctually at 10am, a wonderful aroma of truffles washed over the multitude of prospective purchasers waiting to claim their prizes. I bought a fine 20 gram specimen from truffle hunter Philippe Gay; he has been hunting for over twenty years, his dog is a wire-haired dachshund, and he was circumspect about the source of his product. I found the market an uplifting experience on a dull and drizzly January day. Suitably animated and delighted, my friend and I proceeded to nearby Tremolat for the truly magnificent gourmet lunch at the Dordogne's best restaurant, Le Vieux Logis. An excellent way to spend a winter's day.