Heat the oil in a large non-stick pan over high heat and cook the shanks, in batches, for 1 to 2 minutes on each side or until browned, set aside.
Add the leeks, onion, garlic, thyme and oregano to the pan and cook for 2 to 3 minutes.
Add the flour and cook for 1 to 2 minutes and then add the wine and stock and bring to the boil and then return the shanks and cover with aluminium foil or tight fitting lid.
Place in the oven and roast for 2 1/2 hours, turning every 30 minutes.
Serve with polenta or mashed potatoes and steamed vegetables.
TO FREEZE - shred meat of the bone and divide the meat and sauce into 4 portions and place in zip-lock bags or airtight containers and freeze for up to 3 months. TO DEFROST - place in the refrigerator overnight and allow to thaw completely.