Powdered potato flour: According to legend, Cao Zhi, the son of Cao Cao in the Three Kingdoms, was intelligent and talented since childhood. Cao Cao loved him very much, so he was jealous of his brother Cao Pi. After Cao Cao's death, Cao Pi succeeded to the throne and wanted to kill his brother. Therefore, Cao Zhi was told to go to the temple and write a poem within seven steps, otherwise he would be killed. Cao Zhi thought, "Boiling beans and burning bean soup, beans crying in the kettle, are born from the same root, so why bother to fry each other!" Cao Pi heard the tears. After banishing his younger brother, Cao Zhi was depressed, so he drank and wrote poems and played around. Once in Chang 'an, he ate a bowl of potato powder sold by an old woman along the street, which was pleasant because of its good color and taste. Sui Zhan's poem says, "The entrance is mellow and the aftertaste is long." Praise the delicious taste of potato noodle soup. Subsequently, potato flour became famous, and the business changed from ordinary streets to busy streets. Spread to this day, it has become a famous Chinese food with a beautiful flavor.