How long to soak rajma (and how many whistles)

How long should I soak rajma?

Soak rajma for at least 8 hours, and up to 12. Overnight is the easiest way to get there: soak it after dinner and it's ready for lunch the next day.

Use a big bowl. Rajma roughly doubles in size as it soaks, so cover it with about three times its volume of water. One cup of dried rajma (about 180 g) is enough for 3 to 4 people with rice.

Which rajma you buy changes the timing a little:

Rajma	Soak	Pressure cooker, after soaking
Dark red, large (the common kind)	8 to 12 hours	First whistle on high, then 20 to 25 minutes on low
Light red or speckled (Jammu, chitra)	6 to 8 hours	First whistle on high, then 15 to 20 minutes on low
Not soaked	None	First whistle on high, then 40 to 45 minutes on low, and check every bean

These are ranges, not rules. Cookers, flames and beans differ, so always do the doneness test below before you start the masala.

Rajma soaking time in hot water (the quick soak)

If you forgot to soak it the night before, a hot soak saves the meal:

1. Rinse the rajma and put it in a pot with three times its volume of water.
2. Bring it to a boil and let it boil for 2 minutes.
3. Turn off the heat, cover the pot and leave it for 1 hour.
4. Drain, rinse, and cook in fresh water as usual.

A hot soak gets you close to an overnight soak. Expect a few extra minutes in the cooker.

How many whistles for rajma?

On a standard stovetop pressure cooker, soaked rajma usually needs the first whistle on high heat, then 20 to 25 minutes on low. If you count whistles instead, that's typically 5 to 7 whistles on medium heat. Let the pressure drop on its own before you open the lid; the beans keep cooking while it settles.

For each cup of dried rajma, use about 2½ to 3 cups of fresh water and half a teaspoon of salt.

How to tell rajma is cooked

Take out two or three beans and press each one between your thumb and finger.

• Done: it crushes easily and is creamy all the way through.
• Not done: there's a firm or chalky white centre. Close the cooker and give it another 5 to 10 minutes on low.

Check more than one bean. Rajma cooks unevenly when it's old or wasn't soaked long enough.

Why proper cooking matters with rajma

Raw or undercooked red kidney beans contain a natural toxin, phytohaemagglutinin, that can cause severe vomiting and stomach pain. Soaking alone doesn't remove it. Thorough boiling does.

The UK Food Standards Agency's advice for dried red kidney beans is to soak them, drain and rinse, then boil them vigorously in fresh water for at least 10 minutes. Pressure-cooking rajma until it's soft is well past that point, so a cooker is a safe way to cook it.

Two things to avoid:

• Slow cookers from raw. A slow cooker may not get hot enough to destroy the toxin, and the US FDA warns that warming undercooked beans this way can make them more harmful. Boil first if you want to slow-cook.
• Eating half-cooked beans "to check". Use the press test on a bean you've cooled, and only once it's had its full time.

Why your rajma stays hard

• Old beans. Dried rajma that's been stored for a long time can take much longer to soften, and some never turn fully creamy. Buy smaller packs more often.
• Hard water. If your tap water is hard, soak and cook in filtered water.
• Too short a soak. Under 6 hours usually means uneven beans. Add 10 minutes on low and test again.

Telling your cook

The soak is the step that gets missed, because it happens the evening before. If rajma is for tomorrow's lunch, ask your cook to put it in water at the end of today's visit: "Didi, jaane se pehle rajma bhigo dena." If your cook doesn't come on Sundays, keep rajma off Monday's menu, or soak it yourself on Sunday night.

Questions people ask

How we wrote this: Soaking and safety advice follows UK Food Standards Agency and US FDA guidance on dried kidney beans. Cooker times are ranges: cookers and beans vary, so always check doneness.