Place all ingredients except for onions and chicken in the Instant Pot. Mix them all together.
Place sliced onion rounds inside Instant Pot to line the bottom.
Put the chicken on top of the sliced onion rounds.
Close the lid. Make sure the pointer is in sealing position. Set Instant Pot to pressure cook for 10 minutes. Once done, let the pressure naturally release for at least 15 minutes. Then quick release the rest of the remaining pressure.
Remove the chicken pieces from the Instant Pot. Place the remaining sauce mixture in a blender and food processor and process/blend.
Line a baking tray with aluminum foil and place the chicken pieces on it, making sure there are spaces on the sides. Place in the oven. Broil for 10 minutes. Rotate the tray after 5 minutes to make sure all chicken pieces get broiled evenly.
Place the 1/2 of the blended sauce at the bottom of your serving platter and the other half in a gravy boat.
Place the broiled chicken pieces on top of the sauce in your serving platter. Serve with the sauce in the gravy boat as sauce on the side.