Preparation Combine thyme, orange peel, garlic, salt, and pepper in small bowl. Open lamb on rimmed baking sheet. Using small sharp knife, make twelve 1/2-inch-deep slits on each side of lamb. Fill each slit with 1/2 teaspoon thyme mixture. Rub any remaining thyme mixture over both sides of lamb. Brush lamb lightly with olive oil. (Can be prepared ahead. Let stand 2 hours at room temperature or cover and refrigerate up to 1 day.) Preheat broiler. Broil lamb 4 inches from heat source until brown and crusty and meat thermometer inserted into thickest part registers 125°F to 130°F for medium-rare, about 8 minutes per side. Transfer lamb to platter. Let stand 15 minutes. Slice thinly across grain.
Preparation Combine thyme, orange peel, garlic, salt, and pepper in small bowl. Open lamb on rimmed baking sheet. Using small sharp knife, make twelve 1/2-inch-deep slits on each side of lamb. Fill each slit with 1/2 teaspoon thyme mixture. Rub any remaining thyme mixture over both sides of lamb. Brush lamb lightly with olive oil. (Can be prepared ahead. Let stand 2 hours at room temperature or cover and refrigerate up to 1 day.) Preheat broiler. Broil lamb 4 inches from heat source until brown and crusty and meat thermometer inserted into thickest part registers 125°F to 130°F for medium-rare, about 8 minutes per side. Transfer lamb to platter. Let stand 15 minutes. Slice thinly across grain.