Soup with duck tongues. [Photo by Jiang Dong/China Daily]

The birds used for all of Quanjude's roast-duck dishes are a particular species fed in specific ways to make them fatty, so that after being roasted, the duck skin will be dark-date colored and deliciously crisp, and the meat will be tender and tasty, Sun says.

The new menu also embraces a touch of high technology: After reading a brief introduction of the flavor and history of each dish, diners can scan the 2-D barcodes on the menu to get detailed information about the top 10 most popular dishes in Quanjude restaurants, including their history and how they are cooked.

It's just one way the restaurant hopes to help preserve and promote Chinese culinary heritage, restaurant publicist Liu Hui says.