Sprinkle the shanks with pepper and cinnamon, brown them in a pan until nicely colored.
Place the browned lamb shanks in a slow cooker. Fry a sliced onion and two cloves of garlic in the same pan as you browned the lamb. Once they are slightly colored add the onions and garlic to the shanks. De-glaze the pan with a splash of water, all those charred bits at the bottom of the pan are flavor, don't leave them behind!
Put a large handful of mint in with shanks (I use frozen because I don't have fresh at this time of year.) Cover the shanks with enough stock or water to cover half way. I used leftover carrot water. Cook for 6 to 8 hours. Heavenly!