Clean and wash chicken bones. Soak tamarind in half a liter warm water, remove the pulp, strain and reserve.
Grind scraped coconut with one-cup warm water, extract coconut milk and keep. Reserve the coconut residue also.
Boil chicken bones in about one and half liters of water for about fifteen minutes, skimming the scum from the surface in between.
Add tamarind water, tomatoes, boneless chicken, salt, rasam powder, asafoetida, ten curry leaves and continue cooking.
Cover and simmer till the liquid reduces by half and you start getting a good aroma. Add the coconut residue to the rasam.
Sprinkle chopped coriander and simmer for about three to four minutes. Remove from heat and strain the rasam.
Separate the cooked chicken for garnish and discard rest of the residue. Reheat the rasam, add coconut milk and simmer for a couple of minutes.
Remove from heat and add the cooked chicken cut into tiny bits.
Heat ghee and temper with mustard seeds, red chillies and the remaining curry leaves. Add to the prepared rasam and cover immediately to trap the flavors. Serve immediately.