Pork bao

Cha siu bao is a Cantonese baozi (bun) filled with barbecue-flavored cha siu pork. They are served as a type of dim sum during yum cha and are sometimes sold in Chinese bakeries. There are two major kinds of cha siu bao: the traditional steamed version is called 蒸叉燒包 (pinyin: zhēng chāshāo bāo; Jyutping: zing1 caa1 siu1 baau1; Cantonese Yale: jīng chāsīu bāau) or simply 叉燒包 (chāshāo bāo; caa1 siu1 baau1; chāsīu bāau), while the baked variety is usually called 叉燒餐包 (chāshāo cān bāo; caa1 siu1 caan1 baau1; chāsīu chāan bāau). Steamed cha siu bao has a white exterior, while the baked variety is browned and glazed. Although visually similar to other types of steamed baozi, the dough of steamed cha siu bao is unique since it makes use of both yeast and baking powder as leavening. This unique mix of leavening gives the dough of cha siu bao the texture of a slightly dense, but fine soft bread. Tangzhong, a water roux, is sometimes used to keep the bread soft over long periods of time and aids in improving the texture of the bao.

Source: Wikipedia