1. Cut the oxtail, the carrots, and the onion into large pieces, add salt and pepper to taste, then marinate with the wines and Grappa for 48 hours.
2. Remove the oxtail from the marinade and sauté with the olive oil for five minutes.
3. Add the onions and carrots, and then the wine marinade mixed with the flour.
4. Bring to the boil then cover and simmer for two and a half hours.
5. Serve the meat with its sauce.