Cast-iron skillet

What it is good at

Thermal mass. A cast-iron pan at 220°C contains a great deal of stored heat, so when a cold steak goes in the surface temperature barely drops. A thin pan in the same situation crashes, the meat releases water, and it steams instead of browning.

That makes it the best pan in a domestic kitchen for searing meat, for cornbread and skillet bakes, for anything that goes from hob to oven, and for shallow frying where the oil temperature must stay steady.

It also spreads heat well once it is hot, which is not the same as heating evenly. Cast iron is actually a poor conductor — it takes several minutes to heat through and develops hot spots if rushed. Preheat it slowly and give it longer than feels necessary.

What seasoning actually is

Seasoning is not oil sitting on the surface. It is a hard, slick layer of polymerised fat chemically bonded to the iron: oil heated past its smoke point breaks down and cross-links into a plastic-like film.

That means the layer builds up over time, gets better with use, and is destroyed by anything that dissolves or abrades it — long soaking, harsh detergent, a dishwasher, or a metal scourer used hard.

It also means the commonest seasoning mistake is too much oil. A thick coat goes sticky and tacky rather than hard, because only the layer in contact with the metal polymerises properly. Wipe on the thinnest film you can, then wipe it off again, then heat it.

Seasoning and maintaining one

1. Wash a new pan, dry it thoroughly, and warm it on the hob to drive off every trace of moisture.
2. Wipe a very thin film of a neutral high-smoke-point oil over the whole surface, inside and out.
3. Wipe it off again with a clean cloth until it looks dry. There should be almost nothing visible.
4. Heat it in a 220°C oven upside down for an hour, or on the hob until it stops smoking. Repeat two or three times for a new pan.
5. After cooking, wash with hot water and a brush or a little mild detergent, and dry immediately on the hob.
6. While it is still warm, wipe a trace of oil over the cooking surface.
7. Cook fatty things in it often. Bacon, chips and fried onions season a pan better than any deliberate routine.

Where it is the wrong pan

• Acidic dishes. Tomato sauce, wine reductions and lemon all strip seasoning and can pick up a metallic taste. Use stainless.
• Delicate fish and eggs. Even a well-seasoned pan is not non-stick in the way a coated pan is.
• Anything needing fast temperature changes. Cast iron responds slowly; if you need to drop the heat immediately, it will not.
• Boiling water and stocks. No advantage, and it strips the seasoning.
• Anyone who cannot comfortably lift it. A 28cm skillet full of food is genuinely heavy, and that is a real consideration rather than a minor one.

Common questions