You're not going to stumble across fresh white truffles in any market in Hong Kong, no matter how diligently you search. The season for Tuber magnatum is much shorter than the one for French black truffles (which we'll address in a future Seasons column), making them much more rare and expensive. At wholesale prices, white truffles sell for up to HK$35,000 per kilogram - that's a lot more than most supermarket shoppers are willing to cough up, so the best of them go to top restaurants across the globe. For the past three years, bidders in Hong Kong/Macau have set world records for the price paid for white truffles, which were sold at simultaneous auctions here, in London and in Italy. Last year's monster, purchased by Stanley Ho Hung-sun, weighed 1.5kg and was bought for US$330,000. White truffles can be found in parts of northern Italy; the best are said to come from the area around Alba, in Piedmont. They have a symbiotic relationship with the trees they grow under (such as oak, hazel and beech) and are sniffed out by trained dogs. Global warming is being blamed for the increasing scarcity of white truffles, which are usually available from October to December. Attempts have been made to cultivate white truffles, but without success. Unlike black truffles, which are usually cooked, white ones are almost always served raw because high heat dissipates their elusive but distinctive flavour and aroma. They're best enjoyed simply, as shavings, for instance, added at the last minute to polenta, pasta or risotto. The tuber is also available in jars - although 'white truffle paste' is, in truth, a small amount of truffle mixed with a large quantity of mushrooms. White truffle oil usually contains synthetic flavours and aromas that mimic the Tuber magnatum. It should be used in small quantities. If you do ever buy a fresh white truffle, it should be stored in a glass jar with eggs or rice (they absorb the aroma) and then used up as quickly as possible.