Once the Instant Pot reads "hot", add the coconut oil.
Stir in the onion, and cook for 1 minute, stirring regularly.
Add curry powder, garlic, and ginger. Cook, stirring the entire time, for 1 minute.
Press cancel.
Pour in the broth, and scrape up any browned bits from the bottom of the pot.
Add the chicken.
Top the chicken with diced tomatoes, tomato paste, and salt and pepper.
Close and lock the lid. Press manual high pressure and adjust the cooking time to 8 minutes. Be sure that the pressure release valve is set to sealing. It will take about 10 minutes or so for the pot to come to pressure.
Once the cooking time has finished, let the pressure release naturally for 10 minutes.
Release any remaining pressure by carefully turning the pressure release valve to venting.
Press sauté.
Stir in the coconut milk, and then press cancel.
Notes
Curry powder: Feel free to adjust the amount of curry powder to taste. If you're unsure as to how strong you'd like it to be, I recommend starting with less and then adding more as needed.
Sugar: Some curries call for a bit of sugar to offset the acidity in the tomatoes. Feel free to add a bit of brown sugar to taste if you prefer.