Leg of lamb is elegant, and one leg can feed a crowd. Marinate it with a garlicky herb paste, the longer the better. Overnight in the refrigerator is ideal, but even a few hours at room temperature will help. Just make sure to always pat your lamb dry after marinating; this helps eliminate flare-ups. Butterflied legs of lamb tend to be unevenly cut, giving you thicker and thinner parts. This is good if some of your guests like their lamb more well done than you do, but problematic if everyone likes it rare. If you want rare all around (or well done for that matter), consider cutting the lamb into pieces according to thickness so you can take the thinner ones off the grill first.
01Pat lamb dry with paper towels and place it on a rimmed baking sheet. In a bowl, combine oil, herbs, orange zest and juice, the minced garlic cloves, salt and pepper. Rub mixture all over lamb. Cover with plastic wrap and let marinate at room temperature for 2 hours, or overnight in the refrigerator.
02Meanwhile, prepare the sauce: Place all ingredients in a blender and blend until smooth. Taste and add more salt if you like.
03Heat the grill. Wipe lamb with paper towels, removing most of the rub, then grill until a digital thermometer reads 120 degrees for rare or 130 for medium (about 6 to 15 minutes per side, depending on how you like your meat and how thick the lamb is). If the meat starts to char before it’s done, move it to a cooler part of the grill to finish cooking. Let rest for 10 to 15 minutes before slicing and serving with the yogurt sauce.