Roast leg of lamb with rosemary and garlic pesto

Method

1. Using a sharp knife, make small 2.5cm deep slits all over the lamb, about 2.5cm apart.
2. For the pesto, whizz all the ingredients – using 3 tbsp oil – with some black pepper in a mini food processor (or whizz in a jug using a stick blender) to form a paste. Add more oil if it’s a bit thick.
3. Rub the pesto all over the lamb, pushing it into each slit as you go. Season, then put on a plate, cover loosely with cling film and set aside somewhere cool or in the fridge for at least 2 hours.
4. Take the meat out of the fridge 2 hours before you want to cook it. Heat the oven to 230°C/fan 210°C/gas 8. Scatter the lamb bones, onion, carrot and rosemary in a roasting tin. Rest the lamb on top, then roast for 15 minutes in the middle of the oven. Lower the heat to 180°C/160°C fan/gas 4 and roast for 50 minutes (for rare) or 55 minutes (for medium). A digital thermometer pushed into the thickest part of the meat should read between 50°C and 60°C.
5. Remove the lamb from the oven, lift the joint onto a carving board and cover loosely with foil (discard the bones but reserve the veg in the tin). Rest for 45 minutes or until the gravy and side dishes are ready.