For a truly full-flavored lamb, we recommend marinating it for at least 12 hours, ideally 24.
Place all ingredients, except lamb, in a blender and reduce to a chunky purée. Make twenty small incisions around the leg of lamb with a small, sharp knife. Cover in the marinade, getting inside the incisions and on every side. Cover and marinate in the fridge for 12-24 hours before moving to the next step.
Remove lamb from the fridge 1 hour before cooking. Preheat oven to 325°F.
Place lamb on a roasting pan and cook for 1½ hours. The meat should still be slightly pink.
Let rest for 20 minutes before cutting.
A variation of the Tarragon Roasted Rabbit from The Spice Trekkers Cook at Home