Where does Peking Duck come from? It is a trick question: the dish named for China's capital has its origins in Nanjing, hundreds of kilometres to the south. The tidbit is one of the revelations in a museum opened earlier this month to mark the 150th anniversary of the Quanjude restaurant, now the seven-storey flagship of a chain with franchises as far away as Australia. Statues of roasters, photos of officials dining and menus going back 100 years trace the duck's route from humble waterfowl to culinary institution. No secret ingredients are revealed, but around 20 models detail each stage of the duck's journey to the plate. Slaughtered when it weighs around three kilos, pumped full of air to separate skin from fat, the bird is gutted and filled with boiling water to help a sweet basting syrup penetrate the meat before being dried, coated and roasted. A roast duck style was first developed in the court kitchens of Nanjing, China's then capital in the eastern province of Jiangsu, and the dish only came to Beijing when the Ming dynasty Yongle emperor moved his seat north in the 15th century.