Preheat oven to 160°C. Heat half the oil in a large non-stick frying pan over medium heat. Add onions, carrots, celery and garlic to the pan. Cook, stirring occasionally, for 8 minutes or until softened. Remove from pan and set aside.
Season flour with salt and pepper. Coat osso bucco in flour, shaking off any excess. Heat remaining oil in the frying pan over medium-high heat. Add meat and cook for 2-3 minutes each side or until well browned. Transfer meat to a large ovenproof dish. Spoon over the vegetables.
Increase pan heat to high and add the wine. Boil for 2 minutes, scraping any tasty bits off the base of the pan. Stir in the tomatoes and stock. Bring to the boil. Pour over the meat in the dish. The meat should be covered by the liquid. Cover with a lid and cook for 1 3/4-2 hours or until the meat is very tender and the sauce thickens.
Serve sprinkled with parsley and accompanied by the mash.
