1. Heat one tablespoon of oil in a sauté pan over medium heat. Season chicken with salt and pepper and sauté until golden brown on both sides. Remove from pan.
2. Add onion to the same pan, adding oil if needed. After two to three minutes, when onion is translucent but not brown, add garlic and sauté another minute until garlic is fragrant. Add peppers, scallions, and peas, and sauté another two to three minutes until softened.