Season the bull tail generously with salt and pepper, then lightly dust the meat with flour, shaking off the excess.
Heat a splash of olive oil in a large, heavy pot over medium high heat, about 2 minutes. Sear each bull tail in the hot oil until nicely browned, about 30 seconds per side, then remove the pieces and let them rest on a plate.
Sauté the leek, onion, garlic, red pepper, and tomato using the leftover oil until the vegetables are softened and lightly caramelized, about 10 minutes.
Add the carrots, bay leaves, ginger, and cloves and cook for 1 minute, stirring constantly.
Add the bull tail back to the pan and cover completely with the wine and stock, then bring to a boil. Reduce the heat to a simmer, cover, and simmer for 3-4 hours. It's done when the meat is falling away from the bone. It may need the full 4 hours or longer if the meat is very tough.
Once the meat is tender, remove it and purée the sauce with an immersion blender. (This is optional, but does make the gravy extra thick.)
Spoon the puréed sauce over the rabo de toro. Serve it hot with homemade french fries or mashed potatoes for an authentic Spanish meal.