Season the chicken breasts with salt and pepper. Place the chicken in the multi cooker. Add in the sliced bell peppers and onion.
In a large measuring cup, stir together the balsamic vinegar, honey, soy sauce, garlic and red pepper flakes until well blended. Pour over the chicken, peppers and onion.
Lock the lid and close the release valve. Set the multi cooker to the manual, poultry or pressure cook setting. Set the timer for 8 minutes. When the time has finished, use the quick release valve to release the pressure. Remove lid carefully and let cool slightly. Chicken is done when a meat thermometer inserted in the center reaches 170 degrees F. Remove chicken to a cutting board and let rest for 5 minutes. Slice into serving pieces.
To serve Pressure Cooker Balsamic Chicken with Peppers and Onion, place ½ cup of rice in a shallow bowl. Top with chicken and surround with peppers and onion. Pour the balsamic sauce over the chicken.
