Preheat the oven to 170°C.
Cut 2 cloves of garlic into thin slices.
Zest the lemon, then cut it into rings. Put the zest aside.
Cut about 8 incisions into the meat and put some mint leaves and garlic into each slit.
Put the lemon slices into a roasting dish.
Rub the lamb with oil all over, then put it on top of the lemon slices, then season with salt and pepper.
Cover the dish with foil and roast the lamb in the middle of the oven for about 60/90 minutes. (40 minutes per 500g plus 40 minutes).
Take off the foil for the last 20 minutes of roasting. Baste the lamb with jus too.
Meanwhile, chop the remaining mint leaves and mix with the lemon zest and one garlic clove, minced. Add a drop of olive oil and lemon juice.
When the lamb is cooked through to your liking, brush the gremolata all over it, then cover with foil and rest for 10 minutes.
While the lamb is resting, make some gravy with the jus.
Carve and serve with your chosen side dishes.