Preheat oven to 180 degrees Celsius.
Season the shanks really well and dust in flour.
Heat the olive oil in a large oven safe pot on medium/high heat. Add the lamb shanks and fry off each side for approx. 3 mins or until brown. Remove and set aside.
Turn the heat down to medium low. Heat remaining 1 tbsp of olive oil in the same pot. Add leek and garlic, cook for 2 minutes. Then add the chopped carrot, celery, zucchini and cook for 4-5 minutes.
Add the tomato paste, dried herbs, tinned tomatoes, stock and white wine. Stir very well and let cook for 5-10 mins.
In a casserole dish or Dutch oven, place the lamb shanks at the bottom, pour over the tomato and white wine mix to make sure the shanks are fully submerged. Cover with foil/lid and cook in the oven for 3 hours.
Remove from the oven, remove the lid. Add mushrooms (optional). Stir well and place back in the oven for anyone hour. At this point the meat should be tender and falling away from the bone. If not, just continue to cook for longer.
Remove, scatter with fresh parsley.
Serve on mash potato, polenta or rice.
