- Preheat the oven to 200°C/400°F/ gas 6.
- Puncture the leg of lamb all over with a small, sharp knife. Break off 2cm (¾in) pieces of the rosemary and insert into the puncture holes.
- Sit the leg on scrunched-up foil in a roasting tin. Drizzle over the olive oil and place in the oven.
- After 1 hour 20 minutes, remove from the oven, wrap in foil and rest for 40 minutes. This will give you a perfectly cooked, pink leg of lamb.