Rinse and wash the rice under a cold tap until the water runs clear. Set aside.
Add the tinned tomatoes, garlic, chili, coriander, turmeric and cumin to a bowl and mix in the diced chicken. Cover and marinate for at least 1 hour (overnight would be better).
Add the ghee to the instant pot and set to saute. When the ghee is hot, add the cumin seeds, coriander seeds and chili. Fry for around 1 minute and then add the onion. Fry until softened (around 5 minutes).
Add the pepper and then the chicken together with all the marinade. Fry until the chicken is roughly browned. Season to taste.
Add the hot water and stir everything together. Put a tall trivet into the pot and add the rice with cold water in a suitable container. Put the lid on and set it at high pressure for 10 minutes. Leave under pressure for another 10 minutes and then do a quick release.
Remove the lid, followed by the rice and trivet. Set the pot to saute. Stir the garam masala and chopped coriander stalks into the curry.
Remove around 5 tbsp of liquid to a small bowl with the cornflour. Mix together and stir back into the pot. Bring to the boil and simmer until the sauce has thickened. This should take around 2 minutes.
Serve over the rice, garnished with the coriander (cilantro) leaves.
Video
Notes
If you don't want to do the pot in pot rice, or are serving with chapatis or naan bread instead, just omit this step.