1Pressure cook the soaked horse gram with 1 litre of water for 6 to 7 whistles on medium. Let the pressure release naturally. Strain, keeping all the liquid, and mash a spoon of the gram back into it.
2Soak the tamarind in a little warm water and squeeze out the extract. Heat 1 tbsp oil, splutter mustard and curry leaves, add the horse gram liquid, tamarind, a third of the chilli powder and salt. Simmer until reduced by about half to a thick charu.
3Marinate the chicken with curd, ginger garlic paste, the rest of the chilli powder, turmeric, garam masala and salt while the charu simmers.
4Heat the remaining oil, fry the onion until golden, add half the whole spices and green chillies, then the chicken. Cook covered on medium, stirring now and then, until the chicken is fully cooked with no pink near the bone. Stir in 1 cup of the ulavacharu and simmer until thick.
5Meanwhile, boil plenty of salted water with the rest of the whole spices, add the drained rice and cook until about three quarters done. Drain.
6Spread the rice over the chicken, scatter mint and coriander, drizzle the ghee and a few spoons of ulavacharu. Cover tightly and cook on the lowest heat for 20 minutes.
7Rest for 5 minutes, then mix gently from the side and serve with the remaining ulavacharu and onion raita.
Serve it like this
Serve on a wide plate with a small bowl of extra ulavacharu and onion raita alongside.