Locally in Shanghai and surroundings, they are more often known as ''xiaolong mantou'' . ''Mantou'' means both filled and unfilled buns in southern China, but only means unfilled buns in northern China. To avoid confusion, the name ''xiaolongbao'' is usually used in other areas.
Chinese buns can be divided into two types depending on the level of leavening of the flour skin. Steamed buns made with raised flour are seen throughout the country, and are what is usually referred to as baozi. Steamed buns made with unraised flour are more commonly seen in . The Xiaolongbao belongs to the latter category. This means that its skin is smooth and somewhat translucent, rather than being white and fluffy. The similarity of this appearance to that of jiaozi has meant that the xiaolongbao is sometimes classified as a dumpling outside China. It is, however, different from both steamed and boiled jiaozi in texture and method of production.
Unlike other unraised flour buns, and baozi generally, the xiaolongbao has more filling than dough. It is also small in size, typically about 4 cm in diameter.
Xiaolongbao are traditionally filled with soup and meat, but variations include seafood and vegetarian fillings, as well as other possibilities. The soup inside is created by placing some meat gelatin inside the dumpling before steaming. The steam heat melts the gelatin into soup. In modern times, refrigeration makes it easy to wrap up using chilled gelatine which otherwise might be liquid at room temperature during hot weather.
As is traditional for buns of various sizes in the Jiangnan region, these steamed buns feature a skin that is gathered up into fine folds at the top, prior to steaming.
Traditionally, the Xiaolongbao is a '''' or snack item. The bun is served hot. It is dipped in with ginger slivers, and is traditionally served with a light, clear soup.
The Xiaolongbao has also become popular as a dish in a main meal. In regions and the West, it is also commonly served as a yum cha item.
Frozen ''xiaolongbao'' are now mass produced and a common type of frozen food sold in China and outside. They can be steamed and served on a bamboo basket.
Origins in Shanghai
The Shanghai version of the ''xiaolongbao'' were originally from a town called Nanxiang, a suburb of Shanghai in the Jiading District. The inventor of ''xiaolongbao'' originally sold them in his first store in Nanxiang next to the town's famous park, Guqi Garden. From there on it has expanded into downtown Shanghai and outwards. Two specialist Xiaolongbao restaurants are traditionally regarded as the most authentic. One is the Nanxiang Bun Shop , which derives from the original store in Nanxiang but now located in the City God Temple precinct, is famed for its crab meat-filled buns. Nanxiang Bun Shop has at least 105 years of history and has divisions opened in Hong Kong, Japan, South Korea and Singapore. The other is Gulong Restaurant, at the original site next to Guqi Garden in Nanxiang.
''Xiaolongbao'' in Wuxi tend to be sweeter and have a thinner dough skin, and are juicier than the Shanghai variety.