Lamb, pea and mint pie

1) Heat the oil in a large casserole dish and brown the lamb shanks well all over (you may need to do this in batches). Remove from the pan.
2) Reduce the heat, and add the onions to the dish. Cook until softened.
3) Add the rosemary, wine and thyme. Bring to the boil and cook for 1 minute more. Make sure you scrape any lamb residue from the bottom of the pan.
4) Add the stock, return the lamb bring to a simmer. Cover with a tight-fitting lid, reduce the heat a little and cook until the meat is very tender and falling from the bone 2½ - 3 hours.
5) Half an hour before the end of cooking time remove the pastry from the fridge.
6) Remove the shanks, and leave stock to cool until the fat rises to the surface.
7) Heat oven to 200C/180C fan/gas 6.
8) Spoon off any fat that has separated then bring to the boil and reduce by half.
9) Remove the meat from the bones and arrange in a 30 x 20 x 5cm pie dish.
10) Meanwhile, in a big frying pan, melt the butter, then stir in the flour to a paste and cook for 1-2 mins. Gradually whisk in ladleful’s of the reduced stock until you have a smooth thick sauce.
11) Check the seasoning in the stock then pour over the lamb.
12) Add the peas, spring onions, parsley and mint to the lamb, and gently mix to combine.
13) Brush the rim of the dish with a little egg, then cut thin strips of pastry and stick them on the rim.
14) Top the pie with the rest of the pastry and press down to the edges to stick. Trim the excess and crimp the edges to seal well. Stab with a fork to allow the steam to escape.
15) Brush the whole pie with more egg then bake for 40-45 mins until really golden.