Photography: Romulo Yanes
- 1 bone-in leg of lamb, aitchbone removed by butcher (7 to 8 pounds)
- 2 tablespoons coarse salt
- 2 teaspoons freshly ground pepper
- 2 tablespoons minced garlic
- 2 tablespoons chopped fresh rosemary leaves, plus sprigs for garnish
- 2 tablespoons Dijon mustard
- 2 tablespoons extra-virgin olive oil
- 1 cup chicken broth or water
- 2/3 cup dry red wine
- 1 1/2 cups chicken broth, divided
- 1 tablespoon plus 1 teaspoon all-purpose flour
For the cleanest-looking presentation, trim 1 1/2 inches of flesh from the shank bone with a sharp paring knife. (Your butcher may be willing to do this for you.)
The fell is a thin outer layer of fat that you may find if you buy an untrimmed leg from a butcher. It's very tough, so it's important to remove all of it. A long knife with a sharp thin blade is the best tool for the job.
Trim the excess fat that lies beneath the fell, but leave enough to enrich the meat and gravy. It also crisps up nicely when broiled, which helps give the carved slices great texture. Use shears to trim the fat pads around the hip, or large end.
Make incisions 1 inch long and 1/2 inch deep all over the leg; they?ll allow the aromatic rub to penetrate the meat more easily. Roughening the surface in this way also results in a crisper, more flavorful crust after broiling.
Stir together salt, pepper, garlic, rosemary, mustard, and oil in a small bowl until it forms a wet paste. Spread rub evenly over lamb, working it into the incisions. Let lamb sit at room temperature, about 30 minutes. Meanwhile, preheat oven to 425 degrees.
Transfer lamb, fat side up, to a large roasting pan fitted with a rack, and add broth. Roast lamb 20 minutes. Reduce temperature to 325 degrees, and roast until a thermometer inserted into thickest part of flesh near the bone reaches 130 degrees to 135 degrees (medium-rare), about 55 minutes. Increase temperature to broil; broil until surface sizzles and becomes brown and crisp, about 5 minutes. Transfer lamb to a platter or carving board; let rest at least 20 minutes before carving.
While lamb is resting, remove rack from roasting pan and place pan across 2 burners over medium-high heat. Add wine to the drippings in the pan, bring to a simmer, and reduce by half, scraping up any brown bits with a wooden spoon. Whisk in 1 1/4 cups broth and return to a simmer. Whisk together remaining 1/4 cup broth and flour in a small bowl, then whisk into wine mixture. Simmer until thickened slightly, less than 1 minute. Add any accumulated juices from platter or carving board and pour through a fine sieve into a bowl. Ladle into a gravy boat and serve with lamb.