Heat the olive oil in a large pot over medium-high heat. Add the oxtails and brown on all sides. Remove the oxtails from the pot and set aside.
Add the onion, carrots, and celery to the pot and cook until the vegetables are soft, about 5 minutes. Add the garlic and cook for 1 minute more.
Add the red wine and scrape the bottom of the pot to loosen any browned bits. Simmer for 5 minutes to reduce the wine slightly.
Add the beef broth, tomato paste, bay leaves, and thyme. Return the oxtails to the pot and bring to a boil. Reduce the heat to low and simmer, covered, for 2 hours, stirring occasionally.
Remove the oxtails from the pot and set aside. Increase the heat to medium-high and bring the sauce to a boil. Boil for 10 minutes to reduce and thicken the sauce. Taste and season with salt and pepper, to taste.
Return the oxtails to the pot and simmer for 30 minutes more. Serve hot with the gravy.
Interesting Facts
Oxtail is a traditional winter dish in the United Kingdom.
Oxtail is high in collagen, which can help support joint health and reduce inflammation.