In a skillet over medium heat, sauté chopped onions, garlic, and bell pepper until soft, about 5 minutes.
Add sliced sausage to the skillet and cook until slightly browned, about 3-4 minutes.
Transfer the sautéed mixture to the slow cooker.
Add the rinsed red beans to the slow cooker.
Stir in cayenne pepper, thyme, and bay leaf.
Pour in enough broth to cover all ingredients, typically 6-8 cups.
Cover and set the slow cooker to low. Cook for 7-8 hours, or until beans are tender.
About 30 minutes before serving, prepare rice according to package instructions.
Taste the bean mixture and adjust seasoning with salt and pepper as needed.
Serve the red beans over cooked rice in individual bowls.