Roast all the ingredients listed under rasam powder in a teaspoon of ghee until slightly brown and fragrant. Grind the mixture to a very fine powder. You may have to pulse it several times to get a fine powder. Use a heavy duty mixie or a spice grinder.
Boil the chicken bones with turmeric, salt and water for 10 minutes in a pressure cooker. Switch off the flame and let the pressure from the cooker release naturally,
Strain the stock and remove the chicken from the bones. Discard the bones. Set aside.
Heat ghee in a pan and add in the cumin seeds and curry leaves.
Add in the chopped onions and fry for a couple of minutes.
Add in the chopped tomatoes and the salt. Saute till the tomatoes are cooked.
Add in the ground rasam powder and saute for a couple of minutes.
Add in the shredded chicken and mix well.
Add in the strained stock and let it simmer for 5 minutes.