Clean lamb as needed, washing with water then patting dry with paper towel.
Place on plate or sheet pan.
If lamb is tied together in twine or in a web/net, insert the rosemary underneath it so the sprigs are pressed against flat against the lamb.
Press garlic into lamb, by poking as many small holes with a small knife as needed.
Drizzle a tablespoon or two of olive oil and rub all over lamb.
Season liberally with salt and pepper.
Let lamb sit to room temperature until ready to cook
Preheat grill (gas about 5 minutes, charcoal about 20 minutes) to hot.
Make sure grill is oiled and clean.
Once grill is very hot (place hand a couple inches above the grill grates, and you should have to pull it away within 5 seconds because it's very hot), place lamb on it. You should hear a distinct ""sizzle"" sound. If you do not hear any sizzle, remove the lamb and wait until your gill is hot enough.
11. Let lamb sizzle and sear, creating an outer lightly darkened crust, rotating onto un-seared side every 3-4 minutes. Once outer lamb has beautiful color, turn down grill to low, and close lid. For medium rare lamb cook to an internal temperature of 130 degree F. This will take at least 20 minutes and up to 45 minutes depending on the size of the leg, and the temp of the grill.
Once lamb is cooked to desired temperature remove from grill, and let it rest on a plate for at least 15 minutes. Resting will allow the juices inside the meat to settle in, so when you slice, juices will stay in the meat, rather than bleed out all over the place.
Present as desired (whole cloves, whole citrus, fresh herbs), enjoy!"