One day, chef Li plucked the hair from the duck and wanted to know how to stew the duck with Cordyceps sinensis. Although the duck is very nutritious, it can't see anything dark. After careful consideration, he finally came up with a good idea. He opened the duck's mouth, stuffed some cordyceps into it, and then put it in a pot for stew. This dish is called "Whole Duck with Cordyceps". Wu Zetian thought the duck was well cooked, tender and delicious, and then she ate it every three or two days. After more than a month, Wu Zetian's face improved and her cough stopped. The whole court is happy about her health. One day, Wu Zetian was in a good mood and invited Yushi to dinner. Chef Li Duan served "Duck with Cordyceps sinensis", and Wu Zetian said, "My body has recovered very well, thanks to this dish." The supervisor picked up a chopstick and tasted it. It is really delicious! During the dinner, Wu Zetian asked the supervisor how to handle the murder case of Chef Kang. At this time, chef Li dared to say a few words: "The black thing in chef Kang's duck soup is Cordyceps sinensis. Cordyceps sinensis is warm and sweet, and has the function of tonifying lung and kidney. Mainly used for mental fatigue, cough with excessive phlegm and less blood, asthma and low back pain. Chef Kang did this for the emperor's health ... "Chef Li said, telling Wu Zetian and Yushi the whole process of making" Duck with Cordyceps sinensis "truthfully, and then taking out a black thing from the duckbill. Wu Zetian pondered for a long time and said slowly, "It seems that I was wrong." So he ordered people to release Chef Kang from prison immediately.