Rinse the beans and pick them over, discarding any damaged beans or small pebbles. I have found pebbles in my dried beans, so it’s worth a minute or two to sort through them. Transfer the beans to a 5- to 7-quart slow cooker.
Heat 1 tablespoon of vegetable oil in a large skillet over medium-high heat. Add the sliced sausage and brown, stirring frequently. Transfer to the slow cooker.
Add another 1 tablespoon of oil to the skillet and add the onions, peppers, and celery. Cook for 3 to 4 minutes, until the onion is translucent. Add the garlic and cook for 1 minute longer. Transfer the vegetables to the slow cooker.
Add the bay leaf, Cajun seasoning, chicken broth, and water to the bean mixture and stir to combine.
Cover the slow cooker and cook the beans on high for 5 to 6 hours or until quite tender.
Remove the lid and mash some of the beans. You can use an immersion blender. This will thicken the broth. Taste and adjust the seasonings with salt, more Cajun seasonings, and pepper as needed.
Cover the slow cooker and cook for 30 minutes to 1 hour longer.
Serve the beans with rice and cornbread for a delicious Cajun meal!