Sunday Leg of Lamb

Name: Sunday Leg of Lamb
Ingredients: For the lamb; 4 to 4 1/2 pounds bone-in leg of lamb, bone removed and reserved; 2 tablespoons flat leaf parsley, minced; 2 tablespoons whole grain Dijon mustard; 1 head garlic, roasted; salt and freshly ground black pepper; For the stock; bone from lamb; 1 onion, peeled and cut into quarters; 1 carrot, peeled and cut into chunks; 1 celery stalk, trimmed and cut into chunks; 2 bay leaves; 6 cups water; 3 parsley sprigs