Xiaolongbao (小笼包) are small steamed buns, originally from the Jiangnian region in China, especially connected to Shanghai and Wuxi. Traditionally they are filled with pork, but this can be mixed with other things, like crab meat and roe (eggs). Modern versions of these buns are often contain other meats, seafood or vegetarian fillings.
The buns are wrapped in a dough, which sometimes gets bigger by rising (called a leavened dough), or they're wrapped in a dough which doesn't do this (called an unleavened dough). The buns are then steamed over boiling water to cook them.
It is possible to buy deep frozen Xiaolongbao worldwide, normally in special shops or supermarkets which sell ingredients for Chinese cooking.