Chop all vegetables and whisk together your sauce mixture EXCEPT the cornstarch in a bowl. Set your pressure cooker to saute for 10 minutes.
Add your sesame oil and once it's warmed add your vegetables. Cook until they're beginning to soften, 3-4 minutes. Then pour in your sauce mixture and stir. Allow to heat for 3 min.
Put cornstarch in a small bowl with some of your hot sauce from the pot and whisk together until smooth. Dump this into the pot to allow the sauce to thicken until time is up on saute function, about 2 min. Turn saute function off.
Pour in your frozen popcorn chicken and stir. Add pineapple chunks and stir.
Put pressure cooker lid on and close steam valve. Set to pressure cook high for 4 minutes. Do a quick release.
Stir and serve over rice topped with green onions.