"It's a little messy, but it's the most fantastic lamb I've ever had," says Rosenstein. "You start out with a leg of lamb — bone in or bone out. Get gobs of rosemary — three or four dozen long sprigs. Wrap the lamb in rosemary, then tie that all together with butcher's twine. Roast it for 35-40 minutes in a 425 degree oven. You want to leave it totally rare, just enough to infuse the lamb with that rosemary. Let it cool until you can handle it. Remove the twine and rosemary. Put on a pair of gloves, then pull the muscles apart, remove the silver skin; season and grill to your desired temperature."
Serve it with a big, juicy red, says Rosenstein — a syrah or Barolo, for example.