Heat oil in a pan and add coriander, cumin seeds and stir fry for 3 mins. Keep aside.
In the same pan add sesame seeds and fry till they splutter, remove and set aside.
In the same pan add oil, add the chopped bottle gourd, green chillies, garlic cloves, coriander leaves, a pinch of turmeric powder and fry for 10 mins, remove and cool.
Grind coriander, cumin and sesame seeds, then add rest of the ingredients along with tamarind extract and salt. Grind to a fine paste.
Heat one tsp oil in a pan, add mustard seeds and let them pop, add black lentils and let it turn brown, add curry leaves, asafetida and dry red chillies and stir fry for few seconds.
Pour the seasoning over the ground paste and serve with hot rice.