This recipe highly depends on the quality of lamb stock you're using. Lamb stock is hard come by in our supermarkets, so I tend to make my own. I get lamb bones from the turkish supermarket or directly from the lamb farmer. I then coat them thinly in tomato puree, dust them with flour and then roast them in the oven, until they are heavily browned and very fragrant. Then I dump them in my slow cooker together with carrots, celery, onions and bay leaves and let it simmer for 12 hours. The outcome is a very rich lamb stock, that makes every sauce shine.