In a large skillet, heat the olive oil over medium heat.
Add the diced onion and bell pepper to the skillet. Sauté for about 5 minutes, or until the vegetables are softened.
Stir in the minced garlic and cook for another minute until fragrant.
Add the ground chicken to the skillet, breaking it apart with a wooden spoon. Cook until browned, around 5-7 minutes.
Sprinkle the Cajun seasoning over the cooked chicken and mix well.
Pour in the diced tomatoes, Worcestershire sauce, and apple cider vinegar. Stir to combine everything.
Let the mixture simmer for about 10 minutes, allowing the flavors to meld together. Season with salt and pepper to taste.
Toast the hamburger buns in a separate skillet if desired.
Serve the Cajun spiced chicken mixture on the toasted buns and garnish with chopped parsley.