Xiao long bao (小笼包, literally small basket buns) are the soup-filled dumplings that have become Shanghai's most internationally famous culinary export. A perfect xiao long bao has a very thin, slightly translucent wrapper of hot-water dough, a filling of minced pork (or pork and crab roe in the most prized version) mixed with jellied stock that melts into broth as the dumpling steams, and a pleated seal at the top with 18 or more pleats — each pleat the result of a quick, practiced pinch and fold. The experience of eating xiao long bao — the careful bite to release the hot soup, the slurp of the broth, the chew of the filling and wrapper — is one of the great textural sequences in Chinese eating.
The soup fill: Clarified pork stock (ideally made with pork trotters and skin for high gelatin content) reduced to a concentrate, then set in a shallow tray in the refrigerator until firm — a stock jelly (高汤, gao tang). Cut the jelly into small cubes. Mix with the meat filling — during steaming the jelly melts back into soup inside the sealed dumpling. The stock jelly: 1kg pork trotters and skin, 2L water, ginger, scallion. Simmer 3 hours until very collagen-rich. Strain. The strained stock should set firm enough to cut when refrigerated — it is testing by pressing a finger into the cooled stock. If it springs back, it is sufficiently gelled. The wrapper: 200g plain flour + 100ml just-boiled water. Hot-water dough (tang mian) — essential for the thin, pliable, translucent wrapper. Knead 10 minutes. Rest 30 minutes. Roll to 1mm thickness. Cut rounds 8-9cm in diameter. The filling: 200g minced pork (20% fat), 50g cubed stock jelly, 1 tbsp light soy, 1 tsp dark soy, 1 tsp Shaoxing wine, 1 tsp sesame oil, 1 tsp sugar, 1/4 tsp white pepper, 1 tbsp minced ginger, 1 tbsp minced scallion. The pleating: Place a small amount of filling in the center of the wrapper. Gather the wrapper in 18+ pleats around the filling, twisting and sealing at the top. Steaming: 7-8 minutes in a bamboo steamer lined with parchment paper or napa cabbage leaves.
Insufficient gelatin in the stock: If the stock does not set firm when refrigerated, it contains insufficient gelatin — the soup fill will be too thin and will saturate the wrapper before steaming is complete. Oversteaming: Beyond 8 minutes the wrapper begins to break down and the xiao long bao may rupture.
Fuchsia Dunlop, Land of Fish and Rice (2016); Eileen Yin-Fei Lo, Mastering the Art of Chinese Cooking (2009)