Steaming
The most gentle cook on the list — the piece sits in 100 °C atmosphere, gets no direct flame, gets no oil, and mostly gets itself done by the latent heat of condensation landing on it. That gentleness is the whole point, and it's why steaming is the method for things that would break under pressure or absorb flavor they shouldn't have.
What steaming does that other cooks don't
Steaming holds the surface at 100 °C, no hotter, in a moist environment that doesn't strip any of the piece's own flavor out of it. A carrot that's been boiled has lost most of its flavor to the water; a carrot that's been steamed has given up almost none of it, because there was no water for it to give up to. A fish fillet that's been steamed hasn't been broken up by the mechanical motion of boiling, hasn't been colored by the Maillard window, and hasn't been cooked by the oil's intermediate heat. What you get is the piece itself, mostly unaltered: the shape, the texture, and the flavor are all there, just cooked.
This is also why steaming is the technique of dim sum, of rice, and of steamed egg custard — foods that are delicate, that need to hold their shape, and that lose their identity if you treat them like a braise. The dim sum dumpling is steamed, not boiled, because the wrapper is designed to be a shell that holds a liquid center; the rice is steamed, not boiled, because the water is the cooking medium and it has to stay in the grain, not the pan; the steamed egg custard is steamed because a gentle 100 °C surface, applied evenly, is the only way to set the protein in a way that keeps it silky.
The setup: water, a rack, and a lid
A steamer is, at the minimum, a pot with a little water at the bottom, a rack that keeps the food out of the water, and a lid that's slightly loose enough that the steam can escape but not so loose that it leaks. The water's job is to make the steam, never to touch the food — if the food is sitting in the water, it's boiling now, and the cook has changed. The rack is whatever works: a wire trivet, a folded piece of foil, a plate that sits on a few pieces of crumpled parchment so the steam can go under it. The lid is the one piece that's non-optional, because without a lid the pot is just a pan in a humid room and the whole cook slows to a crawl.
The one real rule of setup: start with the water already hot. If you put the food in a cold pot and wait for the water to come up to a boil, the food has been sitting in a mild, humid environment for ten or fifteen minutes while you wait — that's "poaching at 60 °C," not steaming, and for things like fish and custard it's the difference between a clean result and a grey, weepy one. Bring the water to a rolling boil, then put the food in.
The "dry steamer" trick
In the Chinese kitchen, there's a variation called a "dry steamer" (sometimes "semi-steamed"), used for steamed egg custard and some pork preparations, that uses a different temperature logic. The water in the pot is brought up to a boil and then the heat is dropped so the surface stays at roughly 90–100 °C rather than a rolling 100 °C, and the lid stays on. The result is a slightly slower, gentler set that keeps the egg from curdling into lumps, or the pork from tightening up too much. It's the same principle as a water bath in a bain-marie, with the same payoff: the gentler the surface, the more delicate the texture you can get out of the piece. If you've ever wondered why a restaurant steamed egg custard is silky and yours is lumpy and weepy, this is usually the reason.
Times: what steaming takes
The numbers are shorter than you might expect, because the heat transfer is direct and the piece is already surrounded by the full latent-heat payload of the steam. A small piece of fish (100–150 g) steams in 6–8 minutes; a whole medium fish (400–500 g) in 12–15; a dumpling in 8–12; a plate of greens in 3–5. The pattern is that steaming is fast enough that you don't need to plan around it — the food is done before the water in the pot has even started to worry you about a boil-dry.
Failure modes
- The piece is wet and grey, not cooked. You started with cold water and the food sat in a mild, humid environment while it went up to temperature. Bring the water to a boil first, then add the food.
- The food is in the water, not above it. You're boiling now, and the cook has changed. Check the water level before you start and keep it at a third of the pot depth or less.
- The steamed egg is lumpy and weepy. The surface was too hot, or the mixture was too cold when it went into the pot. Use the dry-steamer temperature and a slightly warmer egg mixture.
- The rice is gummy and the bottoms are sticky. The water level dropped too low, or the lid is sealing so tightly that the condensation is running back into the grain. Check the lid is slightly loose and the water level is enough for the full cook.
In practice
Steamed egg custard (chicken-flavored) is the dry-steamer in action — the one dish where the dry-steamer temperature really matters. Xiao long bao (soup dumplings) is the same technique on a much bigger scale, with the same gentle surface doing the job of setting the wrapper and the filling.