Set pressure cooker to "sear" add oil, and press "start/stop". When hot, add chicken and brown on all sides, about 5-7 minutes. Remove chicken and coat with pesto; set aside.
Add chicken stock and onions to pressure cooker. Place steamer rack in bottom of cooker. Return chicken to steamer rack. Top chicken with potatoes and carrots.
Close and lock lid and set pressure cooker to "poultry". Adjust time to 11 minutes and press "start/stop". When done, quick release and make sure all pressure is released before opening lid.
Carefully open lid. Remove chicken and vegetables and transfer to serving dish.