Heat a pan/vessel, add ghee, cumin seeds, broken red chilly and curry leaves.
Saute for a while and when cumin seeds splutter add chopped tomatoes, crushed ginger, green chillies, turmeric powder and tamarind juice. Add some more water and let it boil for 5 mins.
Add mashed toor dal, salt and dissolved asafoetida. Add water as per the consistency required. Bring it to boil and switch off the flame.
Finally add lemon juice and coriander leaves. Check the taste for sourness and accordingly add lemon juice. Tovve/Kattu saaru is ready to be served with hot steamed rice or idly.