Sort through the beans, discarding any debris. Rinse under cold water and drain. Place the rinsed beans into the slow cooker. Add diced onion, garlic, chopped celery, diced carrots, diced bell pepper, canned tomatoes, sliced sausage, bay leaves, dried thyme, and oregano.
Pour in the chicken or vegetable broth (1 cup less if beans were soaked overnight) until all the ingredients are submerged. Stir gently to combine.
Cover the slow cooker and cook on high heat for 6 to 8 hours if not soaked. Check the beans for tenderness; they should be soft but not mushy.
Around 30 minutes before serving, taste the soup and adjust seasoning as needed. Add salt, pepper, add any cajun seasoning, or hot sauce now if you would like it hot.
Once the beans are tender and the flavors have melded together, remove the bay leaves. Ladle the soup into bowls, garnish with chopped fresh parsley, and serve hot.
Notes
Slow Cooker 15 Bean Soup Soaked Cook Time
If you would prefer using the soaked method:
Rinse and set beans in a bowl with 3x amount of water covering them overnight.
Follow recipe as stated except, use 1 cup less liquid.
Cook on low 8-10 hours until as tender as you'd like.