Flatbreads.

Flatbreads are the oldest breads and the fastest. Unleavened ones — chapati and roti of wholemeal flour, flour tortillas, many 饼 — are rolled thin and cooked on a dry, very hot surface: an Indian tava, a Mexican comal, a Chinese 平底锅 or 鏊子. Because they are only a few millimetres thick, heat reaches the centre in well under a minute (II.2), and if the surfaces have set into skins while the inside is still moist, the water inside turns to steam and inflates the bread into a pocket — the chapati's puff over a flame, the pita's pocket. Too thick, or a surface that cracked, and the steam escapes without puffing.

Leavened flatbreads — naan, pita, many 烧饼 — are yeasted doughs baked in fiercely hot ovens: the tandoor's clay wall, at 400 °C or more, cooks a naan stuck to it in a minute or two, charred in spots and soft inside. Layered flatbreads like 葱油饼 roll oil and scallion into a dough (often 烫面, XXVI.1), coil it, flatten it and pan-fry it, so it separates into flaky layers (XXV.8). The workshop cooks a flatbread.

Below: the seconds for the centre of a flatbread of the thickness you choose to reach the boil on a hot pan, turned every 30 seconds, at the surface temperature you choose (thermal bench, bread composition), with a teaching line: a bread whose inside boils within about a minute, while its skins are still supple and sealed, puffs readily.