Brown the oxtail in a large pot or Dutch oven.
Add the onion, carrots, celery, and garlic and sauté until softened.
Pour in the beef broth and red wine.
Add the thyme and bay leaves.
Bring to a boil, then reduce heat and simmer for 2-3 hours, until the oxtail is very tender.
Season with salt and pepper to taste.
Serve the braised oxtail with the cooking liquid.
