According to legend, in the eighth year of Emperor Kangxi of Qing Dynasty, Wang Zhihe, who came to Beijing from Anhui Province to take the exam, was at the bottom of the gold list. He lived in the guild hall and wanted to go back to his hometown. The traffic was inconvenient and there was no toll. I want to go to Beijing to study and prepare for another exam, which is far from the next exam period. Helpless, I had to make a living in Beijing for the time being. Wang Zhihe's family is not rich. His father opened a tofu mill in his hometown. Wang Zhihe learned to make tofu when he was a child, so he rented several rooms near Anhui Guild Hall, bought some simple utensils, ground several liters of bean curd every day, and peddled them along the street. It's summer now, and sometimes the leftover tofu will soon become moldy and inedible, but it's hard to throw away. Thinking hard about the countermeasures, he cut the tofu into small pieces, dried it a little, found a small jar and salted it. After that, I closed my business and concentrated on my studies, and gradually forgot about it. The autumn wind is cool, and Wang Zhihe wants to go back to his old job and make tofu to sell. Suddenly, I remembered the jar of pickled tofu, and I quickly opened the cylinder cover. A foul smell came to my nose. When I took it out, the tofu was blue-gray I tried it with my mouth and felt it contained a strong aroma. Although it is not delicious, it is also intriguing. I gave it to my neighbor and praised it. Wang Zhihe failed many times, so he had to give up his studies to do business and process stinky tofu in the way he tried in the past. The price is cheap, it can be eaten with meals, and it is suitable for low-income workers. Therefore, the market is gradually opened and business is booming. After raising money, I bought a set of paved houses in Yanshou Street Middle Road, which was produced and sold by myself, and operated in wholesale and retail. According to the purchase contract, it was the winter of the seventeenth year of Kangxi. After Wang Zhihe's original creation of stinky tofu, after many improvements, he gradually explored a set of production technology of stinky tofu. The production scale is expanding, the quality is better and the reputation is higher. In the late Qing Dynasty, it was introduced into the court. Legend has it that Empress Dowager Cixi also likes to eat it in late autumn and early winter, and also lists it as imperial food, but because of its indecent name, it is named "Fang Qing" according to its blue and square characteristics.