Place chicken in the bottom of the Instant Pot. Toss onion over the top. In a small bowl, whisk together the soy sauce, honey, ketchup, garlic, oil, sesame oil, and red pepper flakes. Pour over chicken and turn to coat.
Cook on high pressure for 20 minutes. When finished, quick release and remove chicken and leave the sauce in the pot. Cut chicken into bite-sized pieces.
Set the instant pot to saute on the high setting. Bring to a boil, then whisk in the cornstarch/water mixture. Cook for three or four minutes, whisking now and then until sauce is at desired thickness. Turn off, add the chicken back in and coat with the sauce.
Serve over rice. Garnish with green onion and sesame seeds.
Keywords: Asian, Bargain Meal of the Week, Chicken, Chicken Breast, Chicken Thighs, Green Onion, Honey, Instant Pot, Sesame Chicken, Sesame Seeds