1) Rub leg of lamb well with kosher salt, pepper, and herbs. Wrap tightly in plastic wrap and store in the fridge for at least four hours. This is an optional step, but really improves meat flavor.
2) Unwrap leg of lamb and let come to room temperature for thirty minutes. Heat grill to high heat.
3) Grill lamb for about 5 minutes per side to get a nice crust on the lamb.
4) Move lamb to an indirect heat area of the grill. On my gas grill, I turn off the back burner and turn the other two on low, then move the lamb to the back of the grill.
5) Insert digital thermometer and cover the grill. Turn the lamb every 15-20 minutes until it reaches an internal temperature of 130 degrees for medium rare, 135-140 degrees for medium.
6) When desired temperature is reached, remove lamb and wrap tightly in foil. Let rest for 10 minutes. The temperature should continue to rise another 10 degrees or so.
7) Use a sharp knife to carve out center bone from leg and then slice against the grain. Serve with minted butter.