It is said that its origin is related to a legendary story.
According to legend, Wang Zhan turned out to be a skilled chef who cooked for the emperor every day. Because the emperor was dissolute, corrupt, fatuous and violent, he ate all the delicacies of the world every day, and there was not enough to eat.
One day, the emperor summoned the chef Zhan. Ask him what tastes best in the world? Honest chef Zhan replied that salt tastes the best. He thought that the best food could not be separated from salt, so he answered truthfully. Who knows that the emperor thought salt was the most common thing, but Chef Zhan just mocked me for not knowing how to eat, so he ordered Chef Zhan to be beheaded.
After Zhan was beheaded, other chefs were too scared to add salt to the dishes cooked for the emperor. So the emperor ate salt-free vegetables for more than ten days in a row, and the delicacies were tasteless and weak. It was diagnosed by a physician because he didn't eat salt for many days. The emperor realized that Chef Zhan was right and regretted it. So he made Chef Zhan king and stipulated that on the "memorial day" when Chef Zhan was killed, that is, August 13th, the people would offer sacrifices.
Later, chefs from some restaurants in Sichuan dedicated Chef Zhan to his ancestors. They met every year on August 13th of the lunar calendar to remember and pay homage to his ancestors and make friends.