Cooking in water vapour rather than in water, so nothing is agitated and nothing leaches away.
Technique at a glance
A compact visual model of the lesson. Use the full mechanism and success criteria below when you practice.
Concept
Cooking in water vapour rather than in water, so nothing is agitated and nothing leaches away.
What changes
Steam is water vapour at 100°C, and it carries a great deal of energy — when it condenses on cooler food it releases its latent heat of vaporisation, which is far more than the same mass of hot water would give up.
What good looks like
Steady steam escaping around the lid, not violent jets — a hard boil underneath adds nothing and empties the pan.
Practice counts when you cook
Reading this brief does not change your School state. Finish a real practice dish in Cook mode and log the cook; that cook is the evidence that advances the skill.
What to focus on
Mechanism
Steam is water vapour at 100°C, and it carries a great deal of energy — when it condenses on cooler food it releases its latent heat of vaporisation, which is far more than the same mass of hot water would give up. That makes steaming surprisingly fast despite feeling gentle. Because the food is never submerged, water-soluble vitamins, sugars and flavour compounds stay in it rather than leaching into a pot of water that gets poured away, which is why steamed vegetables taste more strongly of themselves than boiled ones. The other property that matters is that steam finds its way into gaps: a covered pan with a splash of water drives heat into places dry heat cannot reach, which is why a thick vegetable stem, a bao, or a grilled cheese sandwich all benefit from a brief covered moment.
Success criteria
Steady steam escaping around the lid, not violent jets — a hard boil underneath adds nothing and empties the pan.
Green vegetables brighten within the first minute or two; that is the moment they are at their best and it passes quickly.
A skewer meets no resistance, which is the only doneness signal, since nothing browns.
The water underneath never touches the food. If it does, this is boiling.
Failure guards
The pan boiled dry and scorched.
Not enough water for the time, or too hard a boil. Steaming is long enough that a small amount of water disappears.
Vegetables are drab and soft.
Over-steamed. The window between cooked and gone is narrower than for boiling because steam transfers heat so efficiently.
Unevenly cooked, some pieces raw.
Piled too deep. Steam has to circulate; a packed basket cooks the outside and leaves the middle.