There is a Cantonese saying that the Chinese eat everything that flies, except aeroplanes; everything with four legs, except tables; and everything that swims, except submarines - and visitors to Beijing's fast-food market during the Olympic Games will be left in no doubt of that. A stroll among the food stalls of Wangfujing Snack Street, not far from Tiananmen Square, reveals delicacies of every conceivable kind. Laid out in trays and boiling in cauldrons are everything from goat lungs with red peppers to scorpion brochettes, seahorses on skewers, iguana tails, dung beetles and silk worms on a stick, by way...