In a large pan, heat oil over medium heat.
Add the chicken and cook for 5 or so minutes, until lightly browned (don't worry about cooking through). Remove from pan.
Add the potatoes to the pan (adding additional oil if you need).
Cook, stirring every 2 or so minutes for 10 minutes.
Add the chicken back to the pan along with the red onion, snap peas, bell peppers, diced tomatoes, cajun seasoning and salt.
Cover and cook, stirring every 2 minutes, for 10 more minutes. Remove lid and cook for an additional 5 minutes (keep stirring every couple of minutes).
Serve with freshly grated parmesan cheese.