Shēngjiān Bāo (生煎包)

In 1932 a shop called Da Hu Chun opened in Shanghai selling a bun that did something contradictory: it was crisp and chewy on the bottom and pillowy on top, the two textures meeting at a seam halfway up. That bun is the shengjian bao, and the contradiction is the entire design. A single parcel of dough is asked to be deep-fried bread at its base and steamed bun at its crown, in one cooking, in the same heavy iron pan.

The trick is in the pan, which does two jobs in sequence. The buns go in over oil so the bottoms fry to a hard golden crust; then water is poured in around them and a lid clamped down, and the trapped steam cooks the upper two-thirds soft and white. By the time the water has boiled off and the bottoms have re-crisped in the last of the oil, each bun is crunchy underneath, tender above, and the cook lifts them out before the base can scorch.

The filling carries its own sleight of hand. Seasoned minced pork is mixed with a gelatin, often a set meat aspic, that is solid when the bun is pleated shut and turns to liquid soup the moment the pan's heat hits it. So a bun that went into the pan holding a cold lump of jelly comes out holding a mouthful of hot broth, sealed inside the dough by the pleats at the top. It is the same principle as the soup dumpling, scaled up and given a fried floor to stand on.

Everything about the build is a hedge against the soup escaping. The pleats have to be pinched tight or the broth bleeds into the pan and the bun fries hollow. The dough has to be thick enough to hold liquid yet thin enough to eat, which is exactly the line the two schools disagree about. Pan the buns seam-down and the base crisps clean but a loose pleat leaks; some shops pan them seam-up to protect the seal and accept a softer bottom. A scatter of sesame and scallion goes on in the pan so it toasts into the crust rather than sitting on top.

That disagreement over the dough is Shanghai's standing argument about the bun. The older Da Hu Chun school leavens the dough fully, so the bun puffs up thick and bready, like a small fried mantou with a modest amount of juice. The newer school, made famous by the Xiao Yang chain, barely leavens it, keeping the skin thin and taut so the bun holds a dramatic flood of soup and eats closer to a fried xiaolongbao. Neither is wrong; they are two answers to how much bread should stand between you and the broth.

The way you eat one is dictated by the scald inside. Regulars bite a small hole at the top first and sip or let the steam out, because a careless full bite sends a jet of boiling soup across the table or down a sleeve. Then the bun is dipped in dark Chinkiang vinegar, which cuts the richness of the pork fat, and eaten in two or three goes: crisp shattering base, soft yielding top, hot soup, fatty pork, sharp vinegar, all in one mouthful. They are sold by the order of four, and a plate vanishes fast.

The near relations are easy to confuse and worth keeping straight. The xiaolongbao is its thin-skinned steamed sibling, all soup and no fried crust; the shuijian bao and guotie share the fry-then-steam pan but are shaped and filled differently; the plain baozi is the same family of filled bun without the soup or the crust. What makes the shengjian itself is the combination no sibling attempts at once, a yeasted bun fried on one face and steamed on the other around a pocket of soup.

It is, in the end, a bread parcel sealed around a wet filling, which is the oldest sandwich logic there is, dressed up with a fried floor and a mouthful of soup. The genius is that all of it comes out of a single pan in a single cooking, the crisp and the soft and the broth produced together rather than assembled, which is why a good one feels less built than conjured.

A Suzhou Teahouse Snack That Shanghai Made Its Own

The bun did not start in Shanghai, and its name keeps a clue to where it came from. Shengjian first became popular in Suzhou at the start of the 20th century and spread through the Yangtze delta from there, reaching Shanghai and settling in as one of the city's most common breakfasts by the early 1920s. No name is attached to its creation, only a regional snack that found its biggest audience one city over.

The name itself is a small linguistic fossil. In Shanghai it is often called shengjian mantou, even though mantou in standard Mandarin means a plain unfilled bun, because in the Wu-speaking Jiangnan region the word still carries its older sense, where mantou can mean a filled bun just as well as an empty one. The bun is named in a dialect that never made the distinction the rest of the country now does.

The clearest dated anchor is the shop that pulled the snack out of the teahouse and gave it a storefront of its own. Da Hu Chun, founded in Shanghai in 1932, fixed the fully leavened, fluffy style that still bears its name and has served it from the same kind of iron pan for the better part of a century, the moment a teahouse side-snack became a Shanghai institution with an address.