Start with your rice. Add rice and chicken stock to medium pot and cook under medium heat, or according to package directions.
In a large skillet under medium high heat, add sausage, onion, and celery. Cook until sausage starts to brown and onion and celery soften, about 5 minutes. These three ingredients I think really bring a whole lot of flavor to the dish and I wouldn't recommend substituting them or leaving them out.
Stir in both cans of beans and tomatoes. Then add enough Cajun seasoning to your liking. Lower the heat a tad, cover, and simmer for about 10 minutes.
By then, your rice is probably done or close to it, so uncover bean mixture and stir in rice. Heat entire mixture until hot all the way through. Serve hot on a plate and dig in!