char siu bao (simplified chinese: cha shao bao ; traditional chinese: cha shao bao ; pinyin: chashao bao; cantonese yale: chasiu baau) is a cantonese barbecue-pork-filled bun (baozi). the buns are 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.