Heat the olive oil and 1 tablespoon of butter in a Dutch Oven or large stock pot over medium heat.
Add the the bell pepper, celery, and onions and season with salt and pepper. Cook until the vegetables are soft and the onions are translucent. This takes about 5-7 minutes.
Add the garlic and stir in for 1 minute. Now add the remaining tablespoon of butter, Cajun seasoning and the flour. Stir in completely.
Now add in the rice and stir thoroughly.
Pour in the stock and red beans. Raise the temperature to high to bring it to a boil, then reduce it to low to simmer.
Cover the pot and allow the rice to simmer for 20 minutes.
Garnish with chopped celery leaves.