Mix all ingredients for the marinade together.

Add chicken to a Large resealable plastic bag and pour the marinade over it. Seal the bag and marinate in the fridge for at least 1 hour, preferable 4 to 6 hours. Don't throw away the marinade!

Press the Sauté (Normal heat) button on the Instant Pot. When the display reads 'Hot', add the vegetable oil.

Using tongs, take chicken pieces from the plastic bag to the pot one at a time until the bottom of the pot is covered. Don't crowd the chicken.

Cook the chicken just 2 minutes per side (it won't brown much at this phase, and that's fine. You will probably have to do this in two batches). Don't cook it until it is done, it should still be uncooked in the middle. Remove to a plate.

After removing the chicken to a plate, add the onion to the pot and sauté until translucent. Stir occasionally and scraping up all of the browned bits from the bottom of the pot (deglaze).

When the onion is softened, dump the plate of chicken and all of the juices into the pot.

Pour the reserved marinade over the chicken.

Turn off the Sauté setting and put the lid on the pot. Turn the steam release knob to the Sealing position.

Press the Manual (or Pressure Cook) button, then the +/- button or dial to choose 8 minutes. High pressure.

When the cooking cycle has ended, let the pot sit undisturbed to naturally release the pressure for 10 minutes. Then turn the knob and manually release the remaining pressure/steam.

When the pin in the lid drops, open the lid.

Remove the chicken to a clean plate.

Press the Sauté (More heat) button and cook down the remaining liquid in the pot until it becomes a thickened sauce, stirring occasionally. If you want you can stir in a cornstarch slurry to thicken it (equal parts cornstarch and cold water mixed together. Start with 1 ½ Tablespoons each).

Serve over rice (I like Jasmine), and pour the thickened sauce over it.