Dal. It refers both to the wide variety of lentils, peas, and beans used in Indian cooking (also known as pulses), and to the seemingly endless array of dishes you can prepare with them. Cooked simply with spices and aromatics, served with rice or bread, dal is a staple of the Indian diet.
I'm hardly an expert on Indian cooking, but I imagine dal is a malleable genre, where a cook's creativity is given expression in his or her unique amalgam of ingredients. There must be regional variations, with different spicing based on local preference, different lentils or peas or combinations thereof driven by local harvests. I call my own a 'ragged' dal, pieced together from a few different recipes, with a combination of pulses driven by happenstance.
It's a simple enough thing to make, although it may feel fussy the first time through, and while it's nourishing, satisfying, and healthy – it's an excellent source of high-quality protein – it's also quite economical. I like to make a triple batch, as the leftovers reheat beautifully for a quick, easy lunch.