In a small pan, heat 1 tsp oil and add asafoetida, coriander seeds, chana dal, peppercorn, red chilies, curry leaves and fry till the chana dal turns golden.
To this add coconut and fry for a minute. Remove from heat, cool and grind to a smooth paste adding little water. Set aside.
Soak tamarind in 1 1/2 cup hot water and extract the pulp.
Pressure cook the toor dal in 1 cup water with a pinch of turmeric powder. Mash the dal well and set aside.
Cut the bittergourd half in lengthwise and scrap off the seeds and white part from the middle. Now cut them into small pieces.
Heat 2 tsp oil and add the bittergourd pieces. Fry them in medium flame for around 5-6 minutes.
Now add tamarind water, jaggery, turmeric powder and salt. Boil until the raw smell of tamarind goes and bittergourd is cooked.
Now add the ground paste and bring to boil. Once it starts to boil add the mashed dal, salt and mix well. Add little water if needed to bring to a medium thick consistency.
Allow this to boil for 3-4 minutes and remove from heat.
In a tadka pan, heat oil and add mustard seeds. When it pops, add red chillies, curry leaves, asafoetida and pour over the curry.