Black gram

Black gram is a bushy, hairy annual legume with trifoliate leaves and slender pods that contain four to ten seeds each. The whole seeds are small, oval and matte black, about the size of a lentil, and have a thin white line along one edge.

The seed's interior is creamy white. Dried black gram is sold whole with the skin on as sabut urad, split with the skin on as chilka urad, or split and skinned as dhuli urad dal.

When soaked and ground, it forms a notably sticky, mucilaginous batter, which is the key to its use in fermented dishes. The flavour is earthy and slightly sweet.

Black gram was domesticated in India, probably from the wild form Vigna mungo var. silvestris, at least three or four thousand years ago, and it is one of the oldest pulses of the subcontinent. It spread to Southeast Asia, East Africa and the Caribbean through trade and indentured migration.

Today India is the world's largest producer and consumer, with Myanmar a leading exporter.

The name urad comes from Hindi and related languages, and the Latin species name mungo derives from a South Asian word related to the closely related mung bean, to which it is very similar and was once confused.

Black gram is described in ancient Indian agricultural and medical texts, and it features in rituals and in offerings, especially in the south where it is sometimes called ulundu or minapa. It was a pulse of the monsoon season, often grown after rice or in dry-land farming.

South Indian cooking developed fermented batters of rice and urad dal for idli and dosa, a technique that probably evolved over centuries, and in the north the slow-cooked black dal known as dal makhani became a famous Punjabi dish.

Papad, the thin crisp wafer, is traditionally made from urad dal flour. Traders and migrants carried black gram to Myanmar, Thailand, Fiji, Mauritius and the Caribbean, where it joined local cuisines.

India has regularly imported black gram from Myanmar and Africa to meet demand, and the crop is the subject of national pulse policy.

Urad dal is soaked, ground and fermented with rice to make idli, dosa and uttapam batters, and it is also used for vada, papad and the lentil dumplings in dahi vada. Whole black gram cooks into the rich, buttery dal makhani and into other slow-cooked dals.

Split urad is tempered in oil as a spice in South Indian cooking, adding a nutty crunch to chutneys and rice dishes.

Flour is used for breads, and the pulp is a traditional ingredient in some Ayurvedic preparations and as a face mask. Plants are also used as green manure and fodder.

Black gram is a good source of plant protein, fibre, folate, iron and magnesium. Fermenting it into batters may improve digestibility and the availability of some nutrients, and pulses in general are associated with better heart health and blood sugar control in population studies.

Traditional systems recommend it as a strengthening food. There is not much clinical research specifically on urad, so health claims should be moderate.