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.
The sambar is not a South Indian dish. It may have been borrowed from Thanjavur Marathas. Most culinary historians and experts back this theory with suitable evidence.