Lamb shanks braised with sweet potato, rosemary and garlic

100ml olive oil
4 lamb shanks, knuckles removed
salt and pepper
3 celery sticks, chopped
1 carrot, chopped
8 shallots, halved
10 garlic cloves
6 thyme sprigs
3 rosemary sprigs
1 cinnamon stick
3 sweet potatoes, chunks
2 potatoes, scallops
90g pearl barley
2 chillies
2 T tomato paste
3 T honey
2 ½ L chicken stock

Preheat oven 170c. Heat oil and brown lamb, season well with salt and pepper and set aside.  Set pot over medium heat and cook celery, carrot, shallots, garlic, thyme, rosemary, cinnamon 15 mins.  Return shanks to pot plus remaining ingredients.  Simmer 4 mins then cover and cook 2 ¼ hours until meat just coming off bone.  If sauce ends too thin, remove shanks and simmer sauce further 5 mins.