In a large mixing bowl, combine ground beef, breadcrumbs, beaten egg, chopped onion, minced garlic, Cajun seasoning, smoked paprika, Worcestershire sauce, chopped parsley, salt and pepper. Mix thoroughly and let rest for 10 minutes.

Shape the meat mixture into golf ball-sized meatballs, about 1 to 1.5 inches in diameter. Place on a parchment-lined baking sheet.

Heat vegetable oil in a Dutch oven over medium heat. Brown meatballs in batches for 3-4 minutes on each side, then transfer to a plate.

Add another tablespoon of oil if needed to the Dutch oven, sprinkle in flour, and stir continuously for 5-7 minutes until it turns medium brown.

Add chopped onion, green bell pepper, and chopped celery to the roux. Sauté for 5-7 minutes until softened, then stir in minced garlic for another minute.

Gradually pour in beef broth while stirring to combine with the roux. Add bay leaf and adjust seasoning. Bring to a simmer.

Return the browned meatballs to the pot, making sure they're submerged in the broth. Cover and simmer on low heat for 30-35 minutes.

Taste and adjust seasoning, remove bay leaf, and garnish with parsley. Serve over cooked white rice.