Heat the oil in a large frying pan with a lid and brown the chicken for 5-8 mins until golden. Remove and set aside. Tip in the onion and cook for 3-4 mins until soft. Then add the pepper, garlic, chorizo and Cajun seasoning, and cook for 5 mins more.
Stir the chicken back in with the rice, add the tomatoes and stock. Cover and simmer for 20-25 mins until the rice is tender.