Heat a large cast iron pot over high heat. Add the oil and add the oxtail once the oil is hot. Sear the meat on all sides until golden brown. Set aside.

Turn the heat down to medium and add the chopped leeks and garlic. Cook for 5 minutes until the leeks have softened.

Add the wine and scrape off any bits that formed on the bottom of the pot. Add the oxtail back to the pot. Add the stock and bay leaves. Turn the heat to high and bring to a boil. Turn it back down to medium heat to simmer. Simmer for two hours.

Add the chopped carrots and celery and simmer for another hour. Season with salt and pepper.

The oxtail should be fork tender. Remove the bay leaves before serving. You can strip the meat and serve or serve as is with the bone.