Heat the ghee in the Instant Pot using the saute function on "normal." Add the onions and garlic and cook until softened and starting to brown, about 5-7 minutes.
Add the cumin seeds and cook, stirring continuously, for 30 seconds.
Add the remaining spices and stir together for about 20 seconds, no more.
Add the diced tomatoes and stir, scraping anything stuck off the bottom of the pot.
Add the diced chicken and coconut milk.
Set the Instant Pot to pressure cook for 7 minutes. Let the pressure release naturally for 10 minutes, then use the quick release to release any remaining pressure.
Garnish with cilantro and serve with basmati rice and/or naan bread.
Notes
Make sure to stir the spices constantly once you add them and they will burn very easily. Add the tomatoes quickly to prevent burning.
The curry is actually best made a day in advance and eaten leftover. It allows the flavors to really come together.
If the curry is too thin, add a touch of cornstarch slurry in, while mixing continuously, until the desired thickness is reach. Mix 1 tablespoon of water with 1 tablespoon of cornstarch to make a slurry. You can also sauté for 5-10 minutes to allow the sauce to reduce.
Substitute the coconut milk with coconut cream for a thicker, creamier curry in the instant pot.
Add additional salt to taste if desired. I use minimal salt as everyone's salt preferences are different.
For additional flavor, you can brown the chicken thigh pieces before you pressure cook. Just cook them along with the onions and garlic.