Rub the oxtail pieces with salt, pepper, minced garlic, thyme, and bouillon powder. Tightly cover and refrigerate for at least 2 hours or overnight. When ready to cook, remove from the fridge (see notes).
In a large pot, heat oil over medium heat until hot, and then sear the meat, frequently stirring while scraping any browned bits off the bottom until browned.
Add the onions, garlic, thyme, and allspice, then stir for about a minute. Follow with the Worcestershire sauce, browning sauce, tomato paste, bouillon, curry powder, and green onions, and stir for another minute.
Then add 4-6 cups of water (start with 4 cups, adding more if needed).
Bring to a boil and simmer until tender (depending on the oxtail size) for 2-3 hours (4-5 hours at high altitude), occasionally stirring so it doesn't stick to the pan.
About 20-30 minutes before removing it from the heat, add the broad beans and scotch bonnet pepper. Adjust the thickness of the soup with water or stock.
Simmer for 20-30 minutes and adjust salt to taste. Garnish with sliced green onions and enjoy.