It’s the throwaway lines that offer some of the most arresting moments in Invitation to a Banquet, Fuchsia Dunlop’s love letter to several millennia of Chinese gastronomy. That she once cooked 350 duck tongues for a banquet — in Oxford, of all places; that she had her first taste of fermented camel’s milk at a Kazakh circumcision party in Urumqi; or that Yi Yin, the master chef in the service of Duke Huan, the 7th century BC ruler of the State of Qi (in present day Shandong), was said to possess a perfect palate, but w