Heat the sunflower oil (1 tbsp) in a large saucepan over the moderately high heat. Add the chopped chicken breast and cajun seasoning (2 tsp) and fry for 4-5 minutes until the chicken has browned, stirring regularly. Add the chorizo and fry for a few more minutes until the oil is released (you'll know this has happened as the oil in the pan will have a more reddy/orange colour). Remove the chicken and chorizo from the pan and set aside.
Add the onion, celery and garlic to the pan and fry for 2 minutes. Add the peppers and fry for another 2-3 minutes. Add the basmati rice (400g), stir well and cook for a further 1 minute.
Add the chicken stock (1 litre), return the chicken and chorizo to the pan and stir. Bring the pan to the boil, then reduce the heat, cover and simmer for 8 minutes.
Add the chopped tomatoes (400g tin) and cook for a further 5-10 minutes until the rice is tender and the chicken is cooked through. Add a little Tabasco to your own taste (see note 1), season with salt and pepper, and serve.