Lentils are one of the staple foods in India and so there are lentil recipes aplenty. They are so important that I have a separate lentils page with loads of info about lentils.
There are quite a few types of lentils which are used for different things. Urad daal is ground with rice to make a batter which is fermented to make the breakfast dishes idlis and dosas.
Chana daal and masoor daal are probably the most readily available in the West and these are the one commonly used in lentil dishes. Chana daal is like a small chickpea and they are excellent for diabetics. Masoor daal are pink but go orange when you cook them. Other types are moong daal and toor daal.
As well as being very nutritious, they are also very versatile. They can be used to make soups such as sambar in South India, thick spicy stews as in the north of India and Nepal. They are often mixed with other vegetables and dhansak is a well known dish where they are combined with lamb. They are cooked with rice in the popular Indian dish khichdi.
There was once a small Indian restaurant in Soho, London (I don't think it's there any more) which cooked a different daal dish every day for one year.
Or Search the Site to find something