Preheat the oven to 160°C (conventional) [if you’re using an AGA oven, preheat the Baking oven to the same temperature or B3 if you’re using the AGA ER 7].
Combine olive oil, Roast Vegetable Salt and Ras el Hanout in a bowl. Massage the mixture onto the lamb shanks, making sure to cover all sides.
Heat a large heavy based casserole pan over medium heat [or AGA simmer plate (med head)]. Add a couple of glugs of olive oil.
Add the lamb shanks and brown them on all sides. Transfer to a plate and set aside.
Add onion, celery, carrot and garlic to the pan and saute for around 10 minutes, stirring often. Add the tomato paste and stir for another minute.
Put shanks back in the pan and add the stock along with thyme and bay leaf.
Cover with a lid and cook on the middle shelf of the oven [or AGA simmer oven] for 5-6 hours or until the meat is close to falling off the bone. Scatter parsley over the top when ready to serve.