Start by slow-cooking the lamb shanks. First, preheat the oven to 150 degrees Celsius, then spray a casserole pan with oil and heat it over medium-high heat. Brown the lamb shanks in batches, turning them occasionally, for about eight minutes, then return them to the pan.
Chop a tablespoon of rosemary leaves. Pour wine over the lamb and bring to a boil. Let it bubble away for two minutes, then add tomato and sprinkle with chopped rosemary. Bring to a simmer, then turn off the heat and cover the pan tightly with foil. Pop it in the oven and bake for two hours, then remove the foil and bake for another 30 minutes or until the sauce has thickened and the lamb is tender enough to fall off the bone.
To make the pie, increase the oven to 200 degrees, cool the lamb slightly and then use two forks to shred the meat, discarding the bones. Put the lamb mixture in an oven-proof dish, cover with a sheet of puff pastry so the corners hang slightly over the side. Cut four slits in the centre of the pastry so the steam can escape. Take more pastry and cut out leaf shapes to decorate the top of the pie. Sprinkle with more rosemary leaves and sea salt flakes.
Then all you have to do is bake your pie for 20-25 minutes or until the pastry is puffed and golden. This five-ingredient pie makes a delicious meal with steamed veggies or salad on the side