Traditional Tamil Nadu sambar is a tangy and spicy sauce usually had with plain rice and a vegetable accompaniment. Sambar is a ubiquitous dish found in Tamil households.
Squeeze the juice out of the soaked tamarind and bring it to a boil in a deep vessel.
Add the sweet potato, green chilli, sambar powder and salt to the tamarind water and let it simmer on a medium flame for 15-20 minutes.
Once the sweet potato is cooked and the water has reduced to half the quantity, add the pressure cooked dal and mix well. Cook for another 5-10 minutes.
Heat oil in a small kadai. Add mustard seeds and let them splutter. Then add hing and curry leaves. Add this tempering to the cooked sambar.
Garnish with coriander leaves and serve with hot rice.