It is said that this kind of steamed buns originated in 1903, when a man named Lai Ba from Yuxi opened a small steamed bun shop called Shaobailou near Cuihu Lake in Kunming. Lai Ha is a person who likes to think independently, be unconventional, and constantly improve and improve the quality of steamed buns. Once, an old man took his grandson to buy steamed buns. The waiter wrapped the buns and handed them to the old man. The old man smelled the buns and took one to his grandson. Unexpectedly, the grandson didn't catch it and the bun fell to the ground. The buns were immediately smashed to pieces, especially the skin, which was broken into seven or eight pieces. When the little grandson saw that the bun was smashed to pieces, he burst into tears with heartache. At this time, many people gathered around to watch, and they were surprised that the buns were so crispy! At this time, the boss Lai Ba came forward and was also surprised, so he took another bun and gave it to the child. From then on, he seized this business opportunity and launched his signature specialty "posu buns".

The shape of steamed buns is relatively simple. If the shape is too complicated, it will affect the formation of the puff pastry layer. When steaming, use high heat to cook it in one go. When the buns come out of the cage, they are plump and white, with the mouth slightly open and the filling inside vaguely visible. Each bun is lined with a piece of clean white paper to avoid sticking. Tear off the white paper and eat it while it's still hot. The bun will be soft and fragrant, and it will melt in your mouth. If it is a sweet filling, the cloud legs are fresh and salty, and the sugar and honey are sweet but not greasy. The filling of sugar legs is a pioneering work among Yunnan-style pastries and snacks. It can be sweet or salty, meat or vegetable, and is one of the best among the local snacks in China.

Posu buns were originally a local snack in Kunming. Now they have been introduced to major hotels and restaurants. Posu buns can be seen in many high-end banquets, banquets, buffets, and flavored meals. Posu buns are the most popular snack in Kunming and have a unique flavor. In 1903, Lai Ba, a native of Yuxi, opened Shao Bai Lu near the gate of Cuihu in Kunming, specializing in making and selling this kind of steamed buns. The crispy buns are made because of the heavy oil and sugar. It is made of rotten flour (large fermented dough), which is sweet and salty, crisp and soft, and is especially popular among young and old. Children are born to be active. After tasting this delicious food, they will dance and dance. If they are not careful, they will fall to the ground. The buns fell apart immediately, and they were truly called Posu. From then on, the reputation of the buns with sugar legs and Posu spread throughout the city.