Turn Instant Pot to SAUTÉ (skip steps 1-2 and just cook on MANUAL or PRESSURE COOK (high) for 5 minutes if you are in a pinch or prefer. The chicken won’t have that crispy coating.)
Allow pan to heat up for a few minutes then add oil. Cook chicken in batches (placing the browned chicken on a paper-towel lined plate) about 3-4 minutes on each side, until lightly browned. Once all the chicken is browned, add back to the Instant Pot and pour sauce over top.
Close and seal Instant Pot and set the valve to sealing.
Press MANUAL or PRESSURE COOK (high) and set for 3 minutes. Once the 3 minutes is up and the Instant Pot beeps, do a quick release after 5 minutes. Open the lid and transfer chicken to a large serving plate or bowl.
Return inner pot back to the Instant Pot. Press the SAUTÉ button and add additional oil as needed. Toss in the zucchini, bell peppers, and dried red chili peppers. Cook for 2-3 minutes, until tender. Combine the cornstarch with water to make to make a slurry and stir into the Instant Pot. Allow the sauce to bubble and thicken up. Return chicken back to the pot along with the cashews and cook for another 1-2 minutes until everything is heated through.
Sprinkle with sesame seeds, green onions and serve over rice, quinoa, or zoodles, if desired.