Heat the oil in a large frying pan or saucepan. Fry the chicken and onion together until golden brown. Add the red peppers and fry for 2-3 minutes. Stir in the Schwartz Blackened Cajun Seasoning and tomatoes. Bring to the boil, remove from pan and place into an oven-proof dish and cover. Place in a medium oven for 15-20 minutes. Serve with cooked rice.