Cha siu refers to the pork filling; the word bao simply means "bun".
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.
In Hawaii, the item is called Manapua. Its name is a shortening of the Hawaiian mea ʻono puaʻa, meaning, "delicious pork thing." In the U.S. mainland, the Chinese term is commonly used. The Chinese brought this dim sum item with them when they were brought over as plantation workers. In American Samoa and its surrounding islands, the item is referred to as "keke pua'a", literally meaning "pig cake".
This food usually consists of a white bun with a dark pink-colored diced pork filling. The Hawaiian version of the cha siu bao tends to be larger than its Chinese cousin and can be either steamed or baked. The red pork filling's dark pink color comes from marinating the pork with a very small amount of saltpeter prior to slow roasting. The bun is occasionally baked, but more frequently steamed when it is made. Manapua has come to mean any meat-filled or bean-paste-filled bun made with the same dough as described above including locally created versions with hot dogs, currychicken, kalua pig, and even ube (purple yam), which is a popular vegetarian version of the manapua. In Hawaii, freshly prepared or prepackaged frozen manapua may be found in dedicated bakeries, restaurants, and chain convenience stores.