In a large bowl, combine oxtail, soy sauce, browning sauce, chopped onion, garlic, ginger, green onions, allspice berries, black pepper, and thyme. Massage the seasonings into the meat. Cover and refrigerate for at least 4 hours, or preferably overnight.

Remove oxtail from marinade, reserving the aromatics. Heat oil in a large Dutch oven over medium-high heat. Sear oxtail in batches until deeply browned on all sides. Set aside.

Lower heat to medium. Add the reserved onion and garlic from the marinade to the pot and sauté until softened, about 3-4 minutes. Stir in the tomato paste and cook for 1 minute.

Return oxtail to the pot. Add beef broth, water, and the whole scotch bonnet pepper. Bring to a boil, then reduce heat to low, cover, and simmer for 2.5 to 3 hours, or until the meat is tender and falling off the bone.

Remove and discard the scotch bonnet pepper and thyme stems. Stir in the drained broad beans and ketchup. Simmer uncovered for 10-15 minutes for the gravy to thicken. Serve hot.