Dals are an integral part of Indian meals. In some form or the other, they are eaten daily in almost every Indian home.
Dals- lentils or pulses- are varieties of dried beans and peas. They are the main source of proteins for the average vegetarian Indian. Although dal generally refers to split pulses, in actuality there are two types of dal. Whole pulses are known as sabūt dal and split pulses as dhuli dal. The hulling of a pulse is intended to improve digestibility and palatability, but as with milling of whole grains into refined grains, this affects the nutrition provided by the dish, reducing dietary fiber content
Each state in India cooks its dal in different ways. In south, dal is mostly eaten in the form of sambhar. People of Uttar Pradesh swear by toovar dal which is tempered with asafoetida, cumin seeds and sometimes garlic. Punjabis love their dal whole and unhulled, in the form of the delicious dal makhani, or rajma to accompany their rice or chole with their bhaturas.
When I have to describe dal to people in America who haven’t eaten it, the easiest way is to give them a picture of a lentil soup, although dal is a far cry from just a simple soup. The dal that we have is not as watery as soup, generally being creamier (without necessarily adding cream). A well cooked dal is generally quite thick, but sometimes just to keep it light, people thin it down a bit, such being the case for some of the dals that are cooked in southern India.
The tadka or the tempering is what gives a dal its distinct flavor, and is probably what distinguishes it from soups.
Tempering involves heating oil/ ghee in a small pan, to which whole spices are added, which in turn is poured over the cooked dal. Tempering can be simple with a little asafoetida and cumin seeds being tempered in some ghee/or oil, and then mixed in with the cooked dal. Or it can be elaborate by tempering some onions, ginger, garlic and tomatoes in ghee/oil, before adding to the cooked dal.