Peerkangai (ridge gourd) kootu is a common dish in Tamil Nadu. This dish combines moong dal with ridge gourd. It's a great accompaniment with rice and rasam. It can also be eaten along with rotis.
Dhansak, a dish consisting of mutton (goat meat) cooked with a mixture of dals and served with caramelised brown rice.
Sambar as we know it today may have actually originated in the kitchens of the Thanjavur Marathas.