Zest the lemons.
- 1 Heat the oven to 230°C/450°F/ gas 8 (210°C for fan ovens).
- 2 Place the lamb in a roasting tray and pour a little water around it. Mix together the cumin seeds and 1 tbsp olive oil and rub into the top of the lamb. Season and roast for 20 minutes.
- 3 Turn down the oven to 180°C/350°F/gas 4 (160°C for fan ovens) and roast for a further 1 hour, basting once or twice.
- 4 Meanwhile, whizz the herbs, garlic, remaining oil and lemon zest in a processor or pound to a pulp in a pestle and mortar.
- 5 Remove the lamb from the oven and carefully spoon the herb mixture over the top, then return to the oven for a further 15 minutes for medium.
- 6 When cooked to your liking, transfer to a carving board, cover with foil and leave to rest for a few minutes.