Heat oil in a large heavy pot over medium-high heat. Season oxtail with salt and pepper, brown well on all sides in batches, about 10 minutes total. Set aside.
In the same pot, sauté onion and carrots 5 minutes until softened.
Add garlic, cook 1 minute.
Add tomatoes, cook 5 minutes until they break down, scraping up any browned bits.
Return oxtail to the pot, pour in broth, and add fresh herbs.
Bring to a simmer, cover, and cook 2 hours to 2 hours 30 minutes until the meat is completely falling from the bone and the sauce has thickened naturally.
Season with salt and pepper, and serve hot.