*Brought to room temperature. A butterflied leg of lamb has a center portion and two flaps. This recipe uses only the center portion. The remaining portions can be stored in the freezer for later use. The larger flap (sirloin) can be grilled. The smaller one is excellent to use for kebabs. If you’re cooking for a larger group, use the entire leg.
1. Prepare a medium-hot charcoal fire. Or heat oven to 450 degrees and line jellyroll pan with aluminum foil.
2. Combine garlic, rosemary, oil, vinegar, mustard and salt in a small bowl. Rub over entire surface of lamb. (Can be done as long as 12 hours ahead of time, if desired.)
3. Place lamb on grill or baking sheet and sprinkle generously with ground pepper. Grill or bake until it registers 120 degrees on an instant reading thermometer for rare, 22 to 25 minutes; or longer as desired. Let rest for 5 minutes before slicing.