Steamed Bao

Method

1. mix3 min
   warm liquid, not hot
   warm milk + sugar + instant yeast, then flour + salt + baking powder + oil — milk over about 45°C kills the yeast outright, and the salt goes in with the flour rather than into the liquid so it never sits directly on the yeast
2. knead10 min
   by hand on an unfloured counter
   the dough until it stops tearing and pulls back when stretched; bao dough is deliberately stiff and low-hydration, because a slack dough cannot hold its shape in a wet steamer and spreads into a pancake
3. proof60 min
   covered, 26–30°C, until doubled
   the kneaded dough in an oiled bowl — this first rise builds the flavor and slackens the gluten so the dough will roll thin without fighting back
4. prep10 min
   room temperature
   punch the dough flat to drive out the big bubbles, divide into 6 pieces, and roll each into an oval about 4 inches long and 1/4 inch thick; the coarse holes you knock out now are the ones that would otherwise become craters in the finished crumb
5. fold5 min
   oiled crease, over a chopstick
   brush the top of each oval with oil, lay a chopstick across the middle, and fold it over to a half-moon — the oil is the whole point, because unoiled dough welds shut in the steamer and the bun cannot be opened without tearing. Set each on a square of parchment.
6. proof30 min
   in the basket, covered, until puffy and light
   the shaped buns, spaced two fingers apart; the baking powder is insurance for this second rise, giving lift the tired yeast may not have left in it. Underproofed buns burst along the fold; overproofed ones collapse into wrinkles when the heat hits.
7. steam12 min
   lid on, water at a lazy simmer, not a rolling boil
   the basket over simmering water. A hard boil rattles condensation off the lid onto the buns and pockmarks them, and the violent heat sets the skin before the crumb has finished expanding. Nothing browns in here — saturated steam sits at 100°C, well below the Maillard threshold, which is exactly why the bun is all crumb and no crust.
8. rest5 min
   heat off, lid cracked, then fully open
   the buns in the covered basket before lifting the lid all the way. Yank the lid off hot and the trapped steam inside the crumb condenses faster than the starch can set, and the surfaces shrivel into wrinkles that never come back out.