1. Preheat oven to 160 degC. Chop the onions and put into a heavy casserole dish. Place the lamb on top. Add the sliced garlic and season the lamb thoroughly. Rub with the olive oil.
2. Add the bay leaves and the olives. Add the orange zest then peel the orange and cut into segments. Put aside.
3. Pour the stock and wine around the lamb and add the oregano. Put on the lid and cook for 3 hours. Check occasionally and add more liquid if necessary.
4. Remove the lid and add the potatoes(cut into quarters) and orange, replace the lid and return to the oven for a further 45 minutes or until the potatoes are tender. Scatter with fresh oregano before serving with green vegetables. 

Chef's tip The lamb needs to be cooked in a casserole dish with a tight-fitting lid to keep all the moisture locked inside. Check it every so often and add more stock and wine if necessary. A roast with a bone in can be used to give more flavour and can also be left to cook for longer.