Prep the Chicken: Wash, dry, and cube the chicken thighs into bite-sized pieces.
Cook Chicken: Heat the coconut oil in your Instant Pot over the sauté setting. Add the chicken and onion, then cook for 2-3 minutes, or until the onion softens. Stir in the garlic, curry powder, coriander, turmeric, salt, and pepper. Cook for 1 minute or until aromatic.
Combine Ingredients: Add the fire roasted tomatoes and coconut milk. Stir until everything is combined, and scrape up any bits on the bottom.
Cook: Secure the Instant Pot lid and turn the valve to SEAL. Cook for 5 minutes on high pressure. Quick release the pressure when the time is up.
Thicken the Curry: Turn on the sauté setting. Take 1-2 tbsp of the sauce from the Instant Pot and mix it well with the cornstarch. Add the slurry to the Instant Pot, mix well, and let everything come to a bubble. If you'd like the sauce to be thicker, make more slurry.
Garnish and Serve: Garnish with cilantro and serve over steamed rice.