Toor dal soaked overnight: how long and why to soak

Three lengths cover every pot, and all three start from the same rinse. Twenty to thirty minutes at room temperature is the everyday soak for the pressure-cooker dal. Overnight, done in the fridge in warm weather, is the long end: the dal swells fully, cooks the fastest and softens the most. And zero minutes works too, because toor is a split, hulled dal that a pressure cooker softens even when it goes in dry. The overnight soak is also the one on record: two of the four whole pigeon pea preparations in the University of Sydney GI database were soaked overnight before boiling. What a soak changes, and what it does not, is the next section, and the mistakes that spoil a good soak come after the steps.

1. Measure. Half a cup of dry toor dal (100 g) makes a small pot; a full cup (200 g) is the family pot. The timings below hold for any amount, as long as the dal stays under water.
2. Rinse. Swirl the dal in fresh water, pour the water off and do it once more. Foods should be washed well, but not again and again, say the guidelines, because minerals and vitamins leave the dal with the water.
3. Cover with water. Pour clean water until it sits well above the dal, because the dal swells as it soaks.
4. Soak: 20 to 30 minutes, or overnight. Half an hour at room temperature covers the everyday dal. For the fullest softening, leave the bowl overnight in the fridge in warm weather and drain it in the morning.
5. Drain and use fresh water. Pour the soaking water away; it has done its work. Cook the dal in fresh water, about three times its volume, in a pressure cooker: give soaked dal three whistles on medium heat, dry dal four to five, then wait for the pressure to fall on its own.
6. Stop when a grain crushes between two fingers. Soaked dal softens sooner than dry dal, so watch it. Whisk the cooked dal smooth for sambar, or leave a little grain for a home-style dal.

Soaking earns its place in the ICMR-NIN dietary guidelines, which name it among the household methods for grains and legumes that make nutrients more digestible and bioavailable. That is the honest limit of what a soak does. It does not remove the anti-nutritional factors in the dal; the guidelines hand that job to boiling and pressure cooking, which destroy the enzyme inhibitors in pulses and cut the phytic acid in cereals and legumes to a great extent, so minerals like iron, calcium, magnesium and zinc become absorbable. A 2019 review in Current Opinion in Food Science draws the same line: once a pulse is soaked and cooked as recommended, its lectin activity can be completely eliminated. The soak readies the dal; the cook finishes the job.

Two more cooking rules travel with the soak. Cook in just enough water and keep that water: the guidelines say boiling without draining is the best way to hold onto folate in legumes, and that B vitamins and vitamin C are lost if the cooking water is thrown away. And do not overcook: pulses boiled too long lose protein quality through the loss of lysine.

• Cooking in the soaking water. Pour the soaking water away and start the pot with fresh water. It is the cooking water, not the soaking water, that the guidelines tell you to keep.
• Leaving the overnight bowl out in summer. In warm weather a bowl of soaked dal on the counter can turn sour by morning. Use the fridge for the overnight soak, and throw out any batch that smells sour or feels slimy.
• Giving soaked dal the dry-dal cooking time. Soaked dal takes fewer whistles; cooking it as long as dry dal is the road to a paste. The table below has both timings.
• Soaking for days. Overnight is the longest soak this page uses. A bowl left for days can ferment and turn sour, so throw away a batch that smells sour or feels slimy.
• Blaming the soak for a poor pack. Before you blame your soak, look at the pack: oily, plain, polished and unpolished toor differ, and the which toor dal is best guide sorts them.

One set of numbers for toor dal, from washing to the cooked pot; a colder or warmer kitchen shifts the soaking end slightly, not the rule.

These are kitchen timings, and they hold for any pack of split toor. For the dry dal, COWBERRY's pack advice is a sealed container somewhere cool and dry; cooked dal keeps up to two days in the fridge, per UK Food Standards Agency advice. How toor stands next to other dals is the toor dal vs chana dal comparison, and the rest of the cooking, from the first rinse to the tadka, is on the toor dal guide.

Can toor dal be soaked overnight?

Yes, and it is the fullest soak the dal needs. Rinse the dal, cover it with clean water so the dal stays submerged, and leave it overnight in the fridge in warm weather; in the morning, drain and cook in fresh water. Two of the four whole pigeon pea preparations recorded in the University of Sydney GI database were soaked overnight before boiling, so it is a documented way to prepare the pea.

Does toor dal need to be soaked?

No. Toor is a split, hulled dal, so a pressure cooker softens it without any soak. Soaking is optional but shortens the cooking and evens out the softness, so a short soak is still worth the minutes of rinsing. Twenty to thirty minutes is enough for the everyday pot.

How long to soak toor dal before cooking?

Twenty to thirty minutes at room temperature for the everyday dal, or overnight in the fridge in warm weather for the fullest softening; drain before cooking either way. The arhar dal soaking time is the same figure, because arhar is simply the Hindi name for toor dal, and the timings are one and the same.

Why toor dal causes gas?

Like other pulses, toor dal carries sugars named raffinose, stachyose and verbascose, all galacto-oligosaccharides; the small intestine does not digest them, so the colon ferments them and gas is released. The 2019 review of pulse tolerance adds that the sugar explanation has recently been questioned, and that gas settles in most people within a few weeks if eating pulses continues. How much gas varies from person to person.

Is arhar dal and toor dal same?

Yes, one dal under two names. IFCT 2017 records it as red gram in English and arhar dal in Hindi; Marathi says turdal and Tamil says tuvaram paruppu. Every name across India is listed on the names of toor dal page.

Does arhar dal have protein?

Yes. IFCT 2017 prints 21.7 g of protein per 100 g of raw toor dal, along with 9.1 g of fibre and 3.9 mg of iron; these are figures for dry dal, before any soaking. The complete nutrition table, with calories and the glycemic index, is on the arhar dal protein per 100g page.