Pressure cooking

Why the extra heat matters so much

Reactions speed up with temperature, and the ones that matter in a braise — collagen converting to gelatine, starch gelatinising, cell walls breaking down — speed up considerably over a twenty-degree rise. A stew that takes three hours at a simmer will often be done in forty-five minutes under pressure.

Water also cannot evaporate from a sealed pot, so nothing reduces. That is the source of most of the adjustments a pressure-cooker recipe needs: you use much less liquid than you would in an open pot, and if the sauce needs thickening you do it afterwards with the lid off.

What it is good and bad at

Very good — pulses and beans

Dried chickpeas in under an hour from unsoaked. This is arguably the best reason to own one.

Very good — stock

Rich, clear and gelatinous in an hour rather than six, and no evaporation.

Very good — tough cuts

Shin, brisket, oxtail, shoulder. Exactly what pressure cooking is for.

Good — risotto, porridge, rice

Fast and hands-off, at some cost in control.

Bad — anything that needs browning

A sealed wet pot cannot brown. Sear first in the pot, or in a pan.

Bad — green vegetables and delicate fish

They go from raw to destroyed in the time it takes to come up to pressure.

Bad — anything you want to taste as you go

You cannot open it mid-cook without losing the pressure and the time.

Adapting a recipe

• Cut the liquid substantially. Nothing evaporates, so a stew that would take a litre in an open pot may need a third of that. Most cookers need a minimum quantity to come to pressure — check the manual.
• Reduce the time to roughly a third, then check. You can always put the lid back on; you cannot un-cook.
• Brown first, with the lid off. This is not optional if you want the dish to taste of anything.
• Add delicate things after. Peas, greens, herbs, cream and fish go in once the pressure is released.
• Thicken at the end, uncovered, or with a slurry.
• Season at the end. No evaporation means less concentration than you are used to — but taste before adding.

Using it safely and well

• Never fill it more than about two-thirds full, or half full for anything that foams — beans, grains, pasta.
• Keep the pressure valve and the gasket clean. A blocked valve is the one genuine hazard, and modern cookers have several redundant safety mechanisms precisely because of it.
• Learn the two release methods: natural release, where you let the pressure drop on its own, which continues cooking and suits meat and pulses; and quick release, where you vent it, which stops the cooking and suits vegetables and grains.
• Do not force the lid. It will not open until the pressure has gone, by design.
• Follow the manufacturer's instructions for your specific cooker. They differ, and they are the authority on their own device.

Common questions