Crab-Shell Yellow Pastry

The crab-shell yellow is an old pastry of the Jiangsu-Zhejiang-Shanghai-Anhui region; its exact date is given differently across sources, and the dish flourished in Shanghai through the teahouse and old-tiger-stove (boiled-water shop) trade, where many shopfronts kept an upright baking jar and a flat griddle and sold crab-shell yellow and pan-fried buns side by side as they were made. The Shanghai versions made by shops such as Wuyuan (吴苑), Huangjiasha (黄家沙) and Dahuchun (大壶春) became the best known. The name is purely descriptive — after baking the pastry is round and domed like a crab's back shell, with a color like crab roe — and does not indicate any crab in the dough. The savory and sweet fillings are part of the form from the start; the grander savory ones do add crab roe or shrimp.

A good one is light in the hand and crisp through; the top is an even brown-gold studded with toasted sesame, and the first bite breaks the shell into thin flaky sheets that crumble down the front of your shirt. Underneath the layers go soft and faintly chewy from the leavened dough, and the filling arrives warm — a savory one running with scallion oil and pork juice, a sweet one with sugar melting into lard. The sesame should smell roasted, not raw, and the layers should separate cleanly. A poor one is pale and bready with the lamination collapsed into a dense cake, or scorched bitter on the jar wall, or so dry inside that the filling has gone to paste.

The crisp depends on lamination and a very hot jar. A water-oil dough (flour, water, a little lard) is wrapped around a short dough of flour worked with lard alone, then rolled and folded so the lard sits in many thin sheets between the gluten layers; in the heat the lard melts and the trapped water flashes to steam, lifting each layer apart into flakes. A small amount of yeast in the base keeps the bottom tender rather than hard. The disc is brushed with maltose, which browns fast and gives the deep crab-shell color, and rolled in sesame, whose oils toast aromatic in the dry heat. Baked stuck to the curved inner wall of an upright jar (缸炉), the radiant heat sets and colors the top while the dough puffs; the jar runs hotter and drier than an open oven, which is what blisters the surface crisp. Over-handling the dough or too cool a jar melts the lard out before the steam can lift it, and the layers fuse.