Season the oxtail with salt and pepper and brown in the oil. Set aside.
Add carrots, celery, leek and onions, thyme and bay leaves to the pan and cook gently for 10-12 mins until soft. Add garlic and cook for a further 2 mins.
Tip all of this into a casserole together with the oxtail, the wine, the beer, the stock, the tomatoes and some pepper.
Cook at 150 C for about 3-4 hours or until the meat falls off the bone
Remove the meat from the pan and reduce the liquid by half, or until the sauce coats the back of a spoon. Add salt to taste.
Serve garnished with chopped parsley and mashed potatoes