Steaming: Water Level, Condensation, and Stacking

Steam never passes 100°C and still cooks faster than water

This is the heart of steaming and the part that feels wrong.

When steam meets a cold surface it condenses, releasing its latent heat all at once. The heat given off by one gram of steam turning to water is more than five times what one gram of water gives off cooling from 100°C to 60°C.

So at the same temperature, steam delivers heat far faster. And because the food is not submerged, water-soluble compounds stay in it. The difference between boiling and steaming is not temperature; it is those two things (dry heat and moist heat).

If the water touches the food, you are not steaming

Basic, and half of all failures. The water sits 2-3cm deep below the basket and must not reach the food.

And the food goes in after the steam is up. Start it in cold water and the food spends a long stretch merely warm while the water comes to a boil: doughs slump in that window, and gyeranjjim goes bubbly.

On long steams the real hazard is running dry. For anything over twenty minutes, keep a kettle of boiling water to top up with. Cold water breaks the steam.

The drip off the lid is the commonest failure

Condensation collects on the underside of the lid and falls onto the food. Dumplings burst where it lands, steamed buns come out blotched, fish sits in a puddle.

Three fixes, most effective first.

• Stretch a cloth under the lid to catch it. It is also why Chinese steamers are bamboo — the wood absorbs water.
• Set the lid very slightly ajar so the water runs down the wall instead.
• Cover the food with parchment.

Stacking does not work the way people assume

"The top tier cooks less" is a common belief. Steam is the same temperature top and bottom, so there is very little difference in heat.

What actually differs is other things.

• The bottom tier catches more condensation — including what drips from the tier above.
• Aromas travel upward. Steam fish under rice cakes and the rice cakes will smell of fish.

So put strongly flavoured things on the bottom, not the top, and put whatever must stay dry above. And rather than swapping tiers midway, choose a combination that finishes together.

What stops sticking is a liner, not oil

Oiling the basket does not last — the steam washes it away.

• Punctured parchment lets steam through and nothing sticks.
• Napa or cabbage leaves add aroma as well. Common under buuz and mandu.
• Pine needles — this is where the name songpyeon comes from. The aroma is the point; not sticking is a side effect (songpyeon).
• Thin slices of carrot for wrappers thin enough to stick even to parchment, like har gow.

The steamer you want depends on what you are steaming

• Bamboo — absorbs condensation. Best for dim sum (har gow, siu mai).
• Metal — condensation falls straight down. A cloth is effectively mandatory.
• A covered pan — fine for small amounts. A plate resting on three small bowls is a steamer.

When it is done — open at once, or leave it

This one splits.

• Dumplings: open immediately. Trapped steam condenses as it cools, wets the wrappers and glues them to the base. Even in pan-fried-then-steamed gyoza the lid comes off at the end to drive moisture away.
• Leavened dough: wait three minutes. Steamed buns and mantou collapse when the temperature drops abruptly.
• Gyeranjjim: heat off, lid on, two or three minutes. Residual heat sets the centre; opened at once, the middle is underdone.

A dish called "jjim" is not always steamed

A naming trap in Korean. Galbijjim is not steamed at all — it is simmered covered in a soy braising liquid, which is braising. Turning collagen into gelatin needs liquid and time, not steam (braising).

Telling the genuinely steamed dishes — mantu — apart from the ones that only carry the name saves you from choosing the wrong method.