|Ready to go in the oven|
1 bone-in leg of lamb, 4-5 lbs
Salt and pepper
2 heads garlic, peeled
1/4 cup rosemary leaves
Season the lamb in advance if you can. At least an hour is good, and as much as a full day ahead of time brings welcome added flavor to the meat.
Using a sharp, thin-bladed knife, cut small slits into the meat all over it. Sprinkle generously all over with salt and pepper.
Mince the garlic and rosemary together, then combine with enough olive oil to make a paste. Smear this all over the lamb, working it into the slits as well as spreading it on the surface. Place the lamb in a roasting pan that just fits it. Let sit until ready to cook (on the counter is fine for an hour or so; otherwise in the fridge).
Preheat the oven to 425 degrees. Roast the lamb for 30 minutes, then reduce heat to 325. Roast for an additional 15 minutes, then begin testing the temperature. Check it in several places; you want it to be at least 130 degrees for medium rare. Keep in mind that a bone-in roast will take longer to cook near the bone than on the outside. Continue to cook if needed.
Let the lamb sit for 10-15 minutes before carving. Serve warm.