Marinate the oxtail in the red wine for at least 12 hours. Keep turning every couple of hours.
Drain the oxtail and reserve the wine.
Peel the vegetables and, keeping it whole, caramelize in olive oil.
Add the star anise and tomatoes, mix well and cook until most of the moisture is gone from the tomato and it begins to thicken. Keep stirring.
Add the port and Madeira and reduce by half.
Add the wine from the marinade and reduce by half.
Add the oxtail and then both the stocks. Bring to the boil, cover with baking paper and then tin foil and simmer for approx 3-4 hours on a low heat or place in an oven at 140°C for approximately the same time. The meat is cooked when it pulls easily away from the bones.
Allow the cooked oxtail to cool a little in the stock and then remove and drain it. Pick off all the meat while still warm, taking care to keep the pieces as long as possible. Take care to remove the sinew and fat. And reserve until needed in a little of the stock
Pass the sauce through a fine seive and reduce on a medium heat until the consistency of a nice sauce.
Re-heat the picked meat in the sauce.