Heat the oil in a large frying pan.
Dredge the lamb shanks in the seasoned flour and fry in the frying pan for 4-5 minutes, turning regularly, or until browned all over. Place the lamb shanks in the slow cooker.
Deglaze the frying pan with the red wine and continue to cook for 2-3 minutes, or until the volume of the liquid has reduced by half. Pour the liquid into the slow cooker.
Add the onion, rosemary, bay leaves and stock to the slow cooker. The liquid should cover the meat - add more stock or boiling water if needed.
Cook on high for eight hours. Serve with mash.
You’ll need a large slow cooker to fit all of the lamb shanks in.