The beans will need to be pre-soaked. To do this wash beans and place them in a pot with plenty of cold water. Let sit overnight at room temp. Before using, drain and rinse.
In a large dutch oven or other heavy-bottomed pot, add in your oil, onion, bell pepper, and celery. Season the vegetables with salt, pepper, and half of the cajun seasoning. Cook until starting to brown and soft, about 5-8 minutes.
Add in your garlic and cook until fragrant, 30 seconds to 1 minute.
Add your soaked beans. Add water to cover the beans by about 2 inches.
Add in your oregano, thyme, bay leaves, the remainder of the Cajun seasoning, and the bouillon cubes. Stir.
Bring to a soft boil, reduce, and simmer, covered, for 1.5 to 2.5 hours, or until the beans a soft.
Remove cover and remove 1 cup of the cooked beans, set aside. Continue to simmer uncovered to reduce water and beans start to thicken. Remove bay leaves and discard.
Crushed removed beans with a potato masher and return to the pot, stir.
Remove from heat and let sit until cooled and thickened.