Rinse and sort the white beans, removing any debris.
Heat the oil in a large, heavy-bottomed pot over medium heat. Add the sliced sausage and cook for about 5 minutes until lightly browned.
Stir in the onions, bell pepper, celery, and garlic, cooking until the veggies are soft and fragrant.
Pour in the beans, water, Cajun seasoning, bouillon cube (if using) and bay leaf, then bring everything to a boil.
Reduce the heat to a gentle simmer and let it cook uncovered for 2-3 hours, or until the beans are tender, adding more water when needed.
For a creamier texture, mash some of the beans against the side of the pot and stir.
Season with salt, pepper, and more Cajun seasoning to taste.
Just before serving, mix in fresh parsley and green onions, then ladle over hot cooked rice. Enjoy!