1. Wash the dal well. Drain.
2. Add 2 cups of water to dal and allow it to boil for 6-10 minutes until dal is soft.
3. Whisk it with a spoon until smooth.
4. Soak tamarind in water for 8-10 minutes and extract the tamarind juice.
5. In a separate pan, boil tomatoes or any other vegetable of your choice.
6. Add the tamarind juice and ground roasted spices (sambhar powder).
7. After 4-5 minutes, add dal to this mixture.
8. Add curry leaves, fresh coriander leaves and salt to taste.
9. If the mixture is too thin, add a tsp of rice flour paste to thicken the consistency.
10. Simmer for 10-15 minutes.
11. Transfer to a warm serving dish.
12. Heat the oil in a fry pan.
13. Fry mustard seeds and when it splutters, add asafoetida for half a minute and then pour it over the sambhar.
14. Serve hot with steamed rice.

Note: To make sambar powder: Roast, cool and dry grind 1 tsp coriander seeds, 1 tsp cumin seeds, 2 dried red chillies (whole), 2 tsp chana dhal, 1/4 fenugreek seeds.