Marinate the Oxtails: In a large baking dish, combine Worcestershire sauce, brown sugar, allspice, salt, and pepper. Toss the oxtails to coat well. Let them marinate for at least 30 minutes, or overnight for best flavor.

Brown the Oxtails: Heat olive oil in a large pot over medium heat. Brown the oxtails in batches for 2-3 minutes per side. Remove and set them aside.

Sauté Aromatics: Add the chopped onions and minced garlic to the pot, sautéing until fragrant, about 2-3 minutes.

Build the Stew: Return the browned oxtails to the pot. Add the carrots, bell peppers, whole scotch bonnet pepper (do not burst it), bay leaves, thyme, ketchup, apple cider vinegar, and beef broth. Stir well to combine.

Simmer: Cover the pot and cook on medium-low for 2-3 hours until the meat is fall-apart tender and the sauce begins to thicken slightly.

Add Beans and Thicken: Drain the butter beans and toss them with the cornstarch. Stir the beans into the stew. Simmer for another 5-10 minutes to fully thicken the stew.

Serve: Remove the bay leaves and the whole scotch bonnet pepper before serving. Garnish generously with chopped scallions and serve hot with rice.