Shuǐjiān Bāo (水煎包) is the water-fried bun, a filled yeast-dough parcel cooked in a covered pan where a splash of water steams the top soft while the base fries to a hard, lacy crust. The angle is the dual cook. This is one bun finished by two opposing methods at once, steam from above and frying from below, and the entire identity sits in the contrast: a pillowy, fully cooked dome over a crackling browned bottom, often with a thin starch lace webbing the buns together. Get the timing right and you get both textures in a single bite; get it wrong and you get either a soggy bottom or a steam-starved, doughy top.
The build is a leavened, filled bun handled like a potsticker on the back end. A soft raised wheat dough is divided, flattened, and wrapped around a filling, then pleated shut and rested briefly so it stays light. The buns are set seam-up or seam-down into a flat pan with a film of oil and seared until the base just colors. Then water, often a thin flour-water slurry, is poured in and the pan is covered fast so the buns steam through while the liquid cooks off. As the water vanishes the slurry crisps into a brown sheet on the bottom, and a final stretch of dry frying sets that crust hard. Good execution shows a bun that is fully proofed and tender on top with no raw dough at the seam, a base browned to a deep gold that crunches without burning, and a juicy filling that has stayed sealed. Sloppy work shows up plainly: a pan uncovered too soon so the centers stay gummy, too little water so the dough scorches before it cooks, too much oil so the bottom goes greasy instead of crisp, or a weak seal so the filling weeps out and welds the bun to the pan.
It differs from its close relative the shengjian mostly by dough and technique rather than shape. Shengjian leans on a semi-raised or thinner skin and a soup-heavy pork filling finished with a sesame and scallion topping; the water-fried bun runs a fuller-leavened dough and is found widely across northern China with both meat and vegetable fillings. The common savory build is pork with cabbage or chives bound by ginger and soy; vegetable versions lean on more oil and aromatics to carry them, and some regional kitchens scale the buns large enough to eat as a meal on their own. The same pan-and-water finish appears across a family of fried-bottom dumplings and buns, and each of those is its own preparation; what fixes this one is the leavened bun deliberately cooked soft on top and hard underneath in a single covered pan.