Char siu bao exists in two distinct forms that share only the char siu filling: baked (sing bao — the shiny-topped, split-topped bun with its egg-washed golden crust) and steamed (steamed bao — soft, white, slightly pillowy). The dough chemistry of each is different: the baked version uses a standard enriched bread dough; the steamed version uses a dough with a precise amount of baking powder to produce the split that opens the top during steaming.
**Baked char siu bao:** - Standard bread dough (flour, yeast, sugar, milk, butter) — enriched for tenderness. - Filled with char siu (CC-04) in a thick, slightly sticky sauce. - Egg-washed before baking — the egg produces the glossy golden surface. - Baked at 180°C until golden. **Steamed char siu bao:** - Dough with baking powder + baking soda + a small amount of vinegar — the chemical leavening produces the split during steaming. - No egg, no fat, no milk — the dough is white and neutral by design. - The split on top is the quality indicator — correctly made steamed bao splits evenly during steaming.
China: The Cookbook