Wash and put the thuvar dal in a pressure cooker. Add one tomato cut into medium size pieces, turmeric powder and two cups of water. Close with lid and pressure cook for 4 to 5 whistles.
Soak tamarind and extract the juice by adding a cup of water.
In a small mixie, put the black pepper, jeeragam (cumin), red chilli, coriander seeds and grind it to a coarse powder. Before removing add garlic and just run the mixie for one round.
Open the cooker and mash well the dal. Add tamarind extract and the ground powder. Add the remaining tomato cut into medium size pieces. Add a pinch of turmeric powder and salt. Stir well. Add curry leaves and bring to boil. When it starts boiling, remove from stove. Season it with mustard and asafoetida. Finally add chopped coriander leaves and serve with hot rice.