Do you need to soak dried beans?

A bag of dried beans is one of the best-value things in the kitchen, and one of the most intimidating. Mostly because of the soaking: it needs planning, and it is easy to forget. Here is what soaking actually does, when you can skip it, and when you really cannot.

What soaking does

Dried beans take on water as they soak; the University of Nebraska-Lincoln's food extension notes that they can double or triple in size while soaking. The same page says soaking means the beans take less time on the stove and that a hot soak most consistently gives tender beans.

In practice that means:

• Shorter cooking. Soaked beans are ready sooner.
• More even texture. Soaked beans are less likely to end up with split skins outside and chalky centres inside.

What soaking does not do is make bad beans good. Very old beans can stay stubborn whatever you do, so buy from somewhere with a decent turnover.

The three ways to soak

UNL describes three methods:

• Overnight soak: cover the beans with plenty of cold water and leave them in the fridge overnight. The easiest.
• Hot soak: bring the beans and water to the boil briefly, then turn off the heat, cover and leave them for a few hours. UNL's preferred method.
• Quick soak: boil briefly, then leave them covered in the hot water for about an hour. The fastest.

After any of them, drain the soaking water, rinse the beans and cook them in fresh water.

When you can skip it

• Lentils and split peas need no soaking, per the same UNL page. See how to make lentils interesting.
• Small, fresh beans cook perfectly well from dry if you have time and keep an eye on the water level. They just take longer.
• A pressure cooker makes the question much less pressing for most beans.

Unsoaked beans are not a disaster. They are a slower, less predictable dinner.

Red kidney beans: the firm rule

This is the one that matters. Raw or undercooked red kidney beans contain a natural lectin called phytohaemagglutinin that can make people very ill. Australia's Food Safety Information Council advises soaking dried kidney beans for at least five hours, then boiling them vigorously in fresh water for at least ten minutes, and warns against cooking them at low temperatures, such as in a slow cooker, because undercooked beans can be more harmful than raw ones. Wikipedia's phytohaemagglutinin entry notes the same lectin is also found in white kidney beans (cannellini), in lower amounts in some other beans, and that a slow cooker may not destroy it.

So for dried beans in general, and kidney beans in particular: soak, discard the water, then bring them to a proper rolling boil before turning them down to simmer. If you use a slow cooker, boil the beans first. Follow the guidance from your national food safety authority. Tinned beans, the council notes, are already cooked and safe as they are.

Cooking them well

• Use plenty of water and keep the beans covered as they cook.
• Simmer gently after the initial boil, so the skins stay intact.
• Salt is fine. Salting the cooking water seasons the beans properly; many cooks add it from the start, others towards the end.
• Add aromatics. A bay leaf, a garlic clove, a piece of onion, a sprig of sage or rosemary, a Parmesan rind.
• Taste several beans. They are ready when they are creamy all the way through, with no chalkiness.
• Let them cool in their liquid. It keeps them plump and gives you a flavourful broth for soups such as pasta e fagioli.