The trick to mastering barbecue pork buns is time, patience and low-protein flour, writes Tony Tan.
Every time I look at the parade of dim sum delicacies on the trolleys at a yum cha restaurant, one of the first things I hunt for is char siu bao, also known as barbecue pork buns. This Cantonese steamed staple filled with juicy roast pork is a must-eat for most dim sum aficionados.
According to the many dim sum sifus, or masters, I've spoken with, a classic char siu bao must be soft and so well-risen that the bun splits like a smiling dumpling. This might sound simple enough, but the sifus contend that achieving this split is easier said than done. Lau Chor Keung, dim sum sifu of Hong Kong's Grand Hyatt, says that with baking powder and immense patience, one can make acceptable buns that split, while Ho Kam Tai of Melbourne's Red Emperor maintains you need a sourdough starter, and Sammy Chan of Melbourne's Yum Cha Café uses both baker's ammonia and baking powder. Baker's ammonia is a leavening agent: it produces more gas than baking powder, its modern-day successor, and is commonly used to make Greek biscuits and northern European gingerbread. It's incredible to watch how well the buns split and rise when you use baker's ammonia, but this leavening agent is quite foul to the nose. One whiff is enough to make you swoon (not in a good way), and I suspect this is the very reason so few dim sum chefs use this stuff nowadays.
When making the bun dough, some chefs also use a tiny dose of lye water - a strongly alkaline solution - to break down the starch in the flour. Lye water is also used to cure olives and to make noodles and pretzels, and while it's safe to consume, its use is not advisable in a domestic situation because it's hazardous and can cause chemical burns.
For this masterclass, I experimented with several recipes and various combinations of lye water and baker's ammonia to make my buns, and the results were quite spectacular - the buns rose just like the ones you see in yum cha restaurants. But the thought of using these ingredients in a domestic kitchen is slightly scary and not recommended, so the recipe I've developed and included here omits them altogether. In any case, you need a warm environment for the bao dough to rise - ideally, your kitchen should be between 25 and 27C.
The other key ingredient to consider is flour. Cantonese steamed buns are soft and delicate because they're made with Hong Kong flour, a low-protein flour. You can buy it from Asian grocers; ask for Hong Kong flour or low-protein flour, or simply look for a picture of a bun on the packet. Lighthouse brand "biscuit and pastry flour" is also suitable; it's readily available from major supermarkets. If you use plain flour your steamed buns will be slightly heavy, rather more like those found in northern China (which, in my opinion, are also delicious).
Dim sum sifus also insist that char siu bao must be snow-white in colour. To achieve this, you need to use Hong Kong flour, as it's highly bleached. I still remember a Malaysian dim sum "uncle" recommending adding some vinegar to attain a white bao dough, and I've seen other recipes call for milk, but I suspect these additions make little difference to the colour.
Finally, there are a couple of factors to consider when you're making the filling. For the char siu, use pork neck or shoulder for their mix of fat and lean meat. In an ideal world, the pork would be cooked over a charcoal burner or barbecue (for further information, see our char siu recipe), but to keep things simple we've used an oven.
This recipe doesn't use a starter culture or baker's ammonia, and the buns will not split in the classic way, but they'll be soft and delicate.
- 30 gm caster sugar
- ¾ tsp dried yeast
- 220 gm low-protein flour or plain flour
- 1½ tsp baking powder
- 1 tbsp vegetable oil
- ¼ tsp white vinegar
Char siu (barbecue pork)
- 250 gm pork neck
- 1 tbsp Shaoxing wine
- 2 tsp white sugar
- 2 tsp red fermented beancurd (see note)
- 2 tsp hoisin sauce
- 1 garlic clove, finely chopped
- ¼ tsp five-spice powder
- 1 tbsp honey, dissolved in 1 tbsp hot water
Char siu sauce
- 100 ml chicken stock or water
- 1 tbsp caster sugar
- 1 tbsp oyster sauce
- 2 tsp light soy sauce
- ½ tsp dark soy sauce
- 1 tbsp vegetable oil
- 2 tbsp finely chopped ginger
- 2 tbsp finely chopped spring onion, white part only
- 1 small golden shallot, finely chopped
- 1 garlic clove, finely chopped
- 1½ tbsp cornflour, mixed with 50ml cold water
- 1For char siu, cut pork into 3cm-thick, 5cm-wide strips, then combine in a bowl with Shaoxing, sugar, beancurd, hoisin, garlic and five-spice, stir to coat, cover and refrigerate to marinate (at least 2 hours, preferably overnight).
- 2Preheat oven to 220C. Drain pork (reserve marinade), place on a lightly oiled rack placed in a roasting pan, add a little water to pan and roast, basting with marinade and turning occasionally, until cooked and slightly charred (30-35 minutes). Brush with honey mixture while still hot, cool to room temperature, then finely dice and set aside.
- 3For char siu sauce, combine stock, sugar, oyster sauce and soy sauces in a jug, set aside. Heat oil in a wok over high heat, add ginger, spring onion, shallot and garlic, stir-fry until fragrant and just golden (1-2 minutes). Add stock mixture, bring to the boil, reduce heat to medium and simmer for 5 minutes. Add cornflour mixture, stir continuously until thick (1 minute), remove from heat, add diced pork, stir to combine and transfer to a bowl to cool completely.
- 4Dissolve sugar in 125ml lukewarm water in a bowl, add yeast, stir to dissolve and set aside in a draught-free place until foamy (5 minutes). Sift flour and baking powder into a bowl, make a well in the centre, add yeast mixture, oil, vinegar and ½ tsp salt and mix until well combined.
- 5Turn onto a lightly floured surface, knead until soft and pliable (8-10 minutes), then place in a lightly oiled bowl, turn to coat, cover with plastic wrap and set aside in a draught-free place until doubled in size (1-2 hours, or 2-3 hours on a cold day).
- 6Punch dough down, turn onto a lightly floured surface, cut in half, roll one half into a cylinder and cut into 6 pieces (cover remainder with a tea towel). Roll each piece into a ball, then roll out to a 15cm-diameter round. Repeat with remaining dough.
- 7Cut out twelve 20cm squares of baking paper and set aside. Working with one dough round at a time, place a round in your cupped hand and spoon a tablespoon of char siu in the centre. With your other hand, gather and pinch the pastry inwards to form a bun and twist the dough to seal. Place on a square of baking paper and place in bamboo steamers with room to expand. Cover with a tea towel and set aside until slightly risen (30 minutes-1 hour).
- 8Steam buns in batches, covered, over a saucepan of boiling water until puffed and cooked through (12-15 minutes). Serve hot.
Note The char siu recipe, courtesy of the Hong Kong Grand Hyatt's dim sum sifu, Lau Chor Keung, is best prepared a day ahead. Red fermented beancurd is available from Asian grocers.