Finely chop the rosemary, thyme, and mint leaves.
Put the herbs, garlic, olive oil, and lemon juice into a mortar and crush with a pestle until you get a rough paste.
Stir in the lemon zest and season with salt and pepper.
Rub the herb mixture all over the rack of lamb and leave to marinate for about an hour if you have time.
Preheat the oven to 180°C.
Place the lamb in a roasting tin, preferably on a rack.
Roast for 20–25 minutes, depending on how pink you like it.
Rest the lamb for 5 minutes before carving.
Serve with mashed potatoes and seasonal steamed or grilled vegetables.