Should I cook with the lid on or off?

Recipes give the instruction and rarely the reason, which leaves people guessing when the recipe does not say. There is only one thing to work out: do you want the water that is coming out of the food and the liquid to leave the pan, or to go back in?

Step by step

1. Understand what a lid does.It traps steam. That steam condenses on the underside and drips back, so nothing evaporates, the liquid level stays constant, the environment stays wet and everything reaches temperature faster because no heat is escaping as vapour. A lid does not make the pan hotter than boiling — it just stops heat and water leaving.
2. Lid on for anything you want to stay moist.Rice and grains absorbing a measured amount of liquid. Steaming. Long braises and stews where the liquid must not disappear over three hours. Sweating onions gently without colour. Warming through leftovers. Anything where drying out is the failure mode.
3. Lid on to get there faster.A covered pan comes to the boil considerably faster and uses less energy, because it is not losing heat to evaporation. Boil the kettle for pasta water if you can, and put the lid on the pan while it comes up — then take it off when the pasta goes in.
4. Lid off for anything you want browned.Trapped steam settles straight back onto the food, so a covered pan cannot brown. Every searing, frying, roasting and crisping instruction is implicitly lid off. This is the most common lid mistake — covering a pan of browning meat to speed it up and getting grey steamed meat instead.
5. Lid off to thicken and concentrate.A sauce reduces only by losing water. If a stew, curry or gravy is too thin at the end, take the lid off for the last twenty minutes and turn the heat up slightly. This concentrates the flavour as well as thickening, which no amount of cornflour does.
6. Lid off for anything that boils over or needs the surface open.Pasta, potatoes and green vegetables in a lot of water foam up and boil over if covered. Green vegetables also keep a better colour uncovered, because the volatile acids they release escape rather than dripping back onto them.
7. Use the lid ajar as the middle setting.A lid set slightly off the rim keeps most of the heat in while letting some steam out — the right answer for a stock you want to reduce slowly without boiling hard, and for a stew you want thicker at the end but not by much.

Tips

• A glass lid lets you see the pan without lifting it. Every lift of a lid on a long braise costs real heat and time, particularly in the oven.
• For a braise in the oven, a sheet of foil pressed down onto the surface of the liquid under the lid — a cartouche — keeps the exposed meat moist while still allowing some reduction.
• If a recipe gives you a finished liquid quantity and yours is miles off, the lid is usually the reason. Too much liquid at the end means it was covered when it should not have been.
• A tilted lid resting on a wooden spoon across the pan is the classic way to stop a pan boiling over while keeping most of the heat in.

Questions people ask