Xiaolongbao is a type of steamed bun (baozi) from the Jiangnan region of China, especially associated with Shanghai and Wuxi. It is traditionally prepared in xiaolong, small bamboo steaming baskets, which give them their name. Xiaolongbao are often referred to as a kind of "dumpling", but should not be confused with British or American-style dumplings nor with Chinese jiaozi. Similarly, they are considered a kind of "soup dumpling" but should not be confused with other larger varieties of tang bao. In Shanghainese, they are also sometimes known as sioh-lon meu-doe or xiaolong-style mantous.
Shanghai-style xiaolongbao originated in Nanxiang, a suburb of Shanghai in the Jiading District. The inventor of xiaolongbao sold them in his first store in Nanxiang next to the town's notable park, Guyi Garden. From there the xiaolongbao expanded into downtown Shanghai and outward.
Two specialist xiaolongbao restaurants have a particularly long history. One is Nanxiang Mantou Dian (Nanxiang Bun Shop), which derives from the original store in Nanxiang but is now located in the Yu Garden area. It is famed for its crab-meat-filled buns. The other is Gulong Restaurant, at the original site next to Guyi Garden in Nanxiang.
Chinese buns in general may be divided into two types, depending on the degree of leavening of the flour skin. Steamed buns made with raised flour are seen throughout China and are what is usually referred to as baozi. Steamed xiaolongbao made with partially raised flour are more commonly seen in the south. This means that their skin is tender, smoother, and somewhat translucent, rather than being white and fluffy. As is traditional for buns of various sizes in the Jiangnan region, xiaolongbao are pinched at the top prior to steaming, so the skin has a circular cascade of ripples around the crown.
Xiaolongbao are traditionally filled with pork. One popular and common variant is pork with minced crab meat and roe. More modern innovations include other meats, seafood and vegetarian fillings, as well as other possibilities. The characteristic soup-filled kind are created by wrapping solid meat aspic inside the skin alongside the meat filling. Heat from steaming then melts the gelatin-gelled aspic into soup. In modern times, refrigeration has made the process of making xiaolongbao during hot weather easier, since making gelled aspic is much more difficult at room temperature.
Traditionally, xiaolongbao is a kind of dim sum (à la carte item) or xiaochi ("snack"). The buns are served hot in the bamboo baskets in which they were steamed, usually on a bed of dried leaves or paper mat, although some restaurants now use napa cabbage instead. The buns are usually dipped in Zhenjiang vinegar with ginger slivers. They are traditionally served with a clear soup on the side. Around Shanghai, "xiaolongbao" may be eaten throughout the day, although usually not for breakfast. They form part of a traditional Jiangnan-style morning tea (早茶). In Guangdong and the West, it is sometimes served as a dish during Cantonese tea time. Frozen xiaolongbao are now mass-produced and a popular frozen food sold worldwide.
The xiaolongbao is one of kind of tang bao ("soup dumpling") or guantang bao ("soup-filled dumpling"). Another form of tang bao with a differently-textured skin but about the same size is the xiaolong tangbao, a specialty of Wuhan.
^From the Annals of Jiading(a district in Shanghai): "Buns can be made with leavened or unleavened dough. Those made with unleavened dough use clear water for mixing, the skin is thin and the fillings large. It is frequently made in Nanxiang, but is imitated elsewhere, calling it Xiang-style. (《嘉定县续志》: 馒头有紧酵松酵两种，紧酵以清水和面为之，皮薄馅多，南翔制者最著，他处多仿之，号为翔式)