Mǎtí Shāobing (马蹄烧饼) is the horseshoe-shaped sesame flatbread, a baked wheat bun named for its curved, hoof-like form, split or stuffed to carry a savory or sweet filling. The angle is shape as function. The horseshoe curve is not decoration: the bend gives the bread a natural fold and a thicker spine that holds a filling at the bow while the tapered ends stay crisp, so a sandwich built on it depends on the bread's geometry doing the work a flat disc cannot. Get the form and bake right and it reads as a crackly sesame pocket with a contained center; get it wrong and it is just an awkwardly shaped bun.
The build is a baked sesame flatbread shaped before it is filled. A wheat dough, often worked with a little fat for tenderness, is rolled and curved into the horseshoe, brushed with syrup or a wash so sesame seeds adhere across the top, then baked, frequently against the hot wall of an oven, until the outside is hard and deep golden and the sesame is toasted and fragrant. The filling is enclosed before shaping or slid into the split: seasoned minced pork, a salty scallion-and-fat mix, or for the sweet version a sugar or bean paste. Good execution shows a crust that crackles and gives a clean snap, a sesame top that is evenly toasted and aromatic rather than scorched, an interior that stays tender and dry, and a filling that is well seasoned and held at the curve without soaking through to the ends. The failure modes are specific: an under-baked piece comes out pale and doughy with limp sesame; an over-baked one burns the seeds bitter and dries the filling to dust; a curve shaped too thin loses the structural spine and the filling slumps out of the bow; an over-wet filling steams the crust soft and the whole thing turns gummy.
It shifts mostly by filling and by how pronounced the curve is. The savory minced-pork or scallion versions and the sweet sugar or bean-paste readings are the two standard fillings, and the depth of the horseshoe is where bakers tune it toward a generous pocket or a leaner crisp bread. As a sandwich it is the bread carrying most of the character, with the filling a contained accent rather than a heavy load. Plainer round shaobing, the heavily laminated flaky styles, and the thicker griddle flatbreads run on different principles and stand as their own articles rather than crowded in here. What anchors mǎtí shāobing is its geometry against a measured filling: the horseshoe curve gives it a fold and a spine, and the sandwich works only when that shape is exploited rather than fought.