Heat 1 tbsp of vegetable oil in the Pressure Cooker, using the BROWN setting. Add onions, green and red bell peppers, and brown for 2 minutes. Add chicken and soy sauce, and cook for 3 minutes. Add sweet and sour sauce, vinegar, water, and garlic powder. Stir well.
Cover and lock lid. Turn the regulator knob to pressure and select HIGH cooking mode to cook for 10 minutes.
Release pressure by using the quick-release method. When the pressure has dropped, unlock and remove the lid.
Place on serving dish. Garnish with scallions, serve over rice and enjoy!