Char Siu Bao (Steamed Barbecue Pork Buns)

Variations

• Baked char siu bao (烤叉燒包): the same filling in an egg-washed enriched dough, baked. The Hong Kong bakery standard, and a completely different colour and texture — the steamed one is pillowy, the baked one is a sweet soft roll.
• Pineapple-bun topped (菠蘿叉燒包): the baked version under a pineapple-bun crumb crust. More bakery than dim sum.
• Other buns from the same dough: change only the filling and you have the rest of the family — custard (nai wong bao), black sesame, red bean. The rule about setting the filling first holds for all of them.
• Making the char siu yourself: roasting your own char siu is much better. Shop-bought is often already sweet, so cut the sugar in the sauce. The braised pork from hong shao rou also works, though it is richer and fattier.
• Without a steamer: 2cm of water in a wide pan, a trivet, a plate on top, and a cloth tied over the lid. The cloth is what stops condensation dripping and blotching the surface.
• The others in the same steamer: har gow, siu mai and xiaolongbao are all thin-wrapper dumplings; char siu bao is the only leavened one. Korea's mandu and Japan's gyoza are on the dumpling side too.
• Freezing: cool the steamed buns and freeze them individually for a month. Re-steam from frozen for 8-10 minutes; a microwave makes the outside tough (freezing and thawing).

Tips

• The filling must be set before it goes in. Nearly every failure traces back to this. Warm, loose filling leaks while you shape and wets the dough from the inside, leaving a raw base. Chill it until it holds its shape on a spoon (thickening sauces).
• Use low-protein flour. White, fluffy bao come from flour with little gluten; bread flour gives you something chewy and yellow. Ten percent cornflour makes it whiter still (choosing flour, dough and gluten).
• Use yeast and baking powder both — in that order. The baking powder is kneaded in only after the yeast has finished the first prove. Added at the start it spends itself during that hour and has nothing left when the bun hits the steam (fermentation basics).
• Seam upward. The opposite of every other dumpling. The sealed side is the weakest point as it steams, so that is where it opens, and that split is the mark of a well-made one (wrapping and sealing).
• Only put them on once the steam is fierce. Warmed up gently, the surface sets before it can burst and they come out smooth. Split tops need hard steam from the first second (steaming).
• Do not lift the lid. One look during the twelve minutes drops the temperature and they sink.
• Tie a cloth over the lid. Condensation dripping off the lid soaks patches of dough and leaves yellow blotches.
• Rest five minutes after steaming. Straight from hot steam into cold air the surface shrivels. Crack the lid and let them come down slowly (serving temperature).
• A teaspoon of vinegar whitens the dough. A Hong Kong dim sum trick with no effect on taste. It is not bleaching — flour pigments simply show less in acid.
• Put onion in the filling. Char siu alone is dry; finely chopped onion, softened first, adds both moisture and sweetness (building umami).
• Do not cut the sugar. The 50g in the dough is not there for sweetness — it feeds the yeast and softens the crumb. Less of it and the buns rise less and eat tougher (what sugar does).
• Space them in the steamer. They rise once more while proving and again while steaming. Packed together they press into each other and lose their shape.