1. Add ground beef, breadcrumbs, egg, finely chopped onion, garlic, Cajun seasoning, smoked paprika, Worcestershire sauce, parsley, salt, and black pepper to a large bowl. Mix gently until combined.

2. Shape the mixture into medium meatballs, about the size of a golf ball.

3. Heat part of the vegetable oil in a Dutch oven or heavy pot over medium heat. Brown the meatballs in batches on all sides, then transfer them to a plate.

4. Add the remaining oil to the same pot. Stir in the flour and cook, stirring constantly, until the roux becomes medium brown and smells nutty.

5. Add chopped onion, bell pepper, and celery. Cook until softened, then stir in the garlic for about 30 seconds.

6. Slowly pour in the beef broth while stirring to create a smooth gravy. Add the bay leaf and adjust seasoning if needed.

7. Return the meatballs to the pot. Cover and simmer gently for 30 to 35 minutes, until the meatballs are cooked through and the gravy has thickened.

8. Remove the bay leaf, garnish with parsley, and serve hot over cooked white rice.