Herb-Crusted Roast Leg of Lamb with Garlic and Rosemary

Herb-Crusted Roast Leg of Lamb

A 5- to 6-pound bone-in leg of lamb roasts under a coating of fresh rosemary, thyme, parsley, garlic, and Dijon. The herb paste browns into a dark, adherent crust without breadcrumbs. A brief high-heat start builds color, then a lower oven temperature gives the center time to cook without scorching the herbs.

Legs vary in shape and thickness, so the roasting time is an estimate. Check the thickest meat with a thermometer rather than judging doneness by the clock or the color of the sliced lamb.

Ingredients for Herb-Crusted Roast Leg of Lamb

• 1 bone-in leg of lamb, 5 to 6 pounds (about 2.5 kg)
• 2 teaspoons kosher salt, or to taste depending on the salt brand
• 1 teaspoon black pepper
• 2 tablespoons Dijon mustard
• 2 tablespoons olive oil
• 6 garlic cloves, finely chopped or grated
• 2 tablespoons finely chopped fresh rosemary
• 1 tablespoon finely chopped fresh thyme leaves
• 2 tablespoons finely chopped fresh flat-leaf parsley
• A few fresh thyme sprigs for serving, optional

How to Roast Herb-Crusted Leg of Lamb

1. Preheat and season: Place an oven rack in the center position and preheat to 425°F (220°C). Pat the lamb dry and set it on a rack in a sturdy roasting pan. Season all over with salt and pepper.
2. Apply the herb coating: Stir together the Dijon, olive oil, garlic, rosemary, thyme, and parsley. Spread the mixture over the lamb and press it gently onto the dry surface.
3. Start at high heat: Roast uncovered for 15 minutes, until the coating begins to brown. Do not add liquid to the pan or pour it over the crust.
4. Lower the heat: Without removing the lamb, reduce the oven to 325°F (165°C). Continue roasting uncovered, rotating the pan once if the oven browns unevenly. Loosely tent the lamb with foil if the herbs become very dark before the center is done.
5. Check for doneness: Begin checking after about 1 hour 30 minutes of total roasting, then check every 10 to 15 minutes as needed. Insert an instant-read thermometer into the thickest meat without touching bone; check another thick area if the leg is irregularly shaped. Remove the lamb when it reaches 145°F (65°C). Total roasting time is roughly 1 hour 45 minutes to 2 hours 30 minutes, but the thermometer determines when it is done.
6. Rest and carve: Rest for 15 to 20 minutes before cutting thick slices across the grain with a sharp knife. Arrange several slices in front of the remaining roast and add thyme sprigs, if desired.

How to Keep the Herb Crust from Scorching

Check the coating as the lamb cooks at 325°F. It should become deeply browned, not blackened into ash. If it darkens too quickly, tent the roast loosely with foil so the center can keep cooking without exposing the herbs directly to the oven heat. Do not wrap the roast tightly or treat crust color as a doneness test.

Why Roasting Time Varies

This timing is designed for a 5- to 6-pound bone-in leg. A boneless leg or a roast of a different size or shape can cook at a different rate, and thicker areas of the same leg may finish later than thinner ones. Use the 145°F thermometer reading in the thickest meat, followed by at least a 3-minute rest, rather than relying on the estimated time. The longer rest in the method also makes the lamb easier to carve. The center may remain rosy, but color alone cannot confirm doneness.

Serving the Lamb

Serve thick slices with roasted potatoes and a green vegetable, or with a simple salad and warm bread. For another oven-roasted centerpiece, try classic roast turkey.

How to Store and Reheat Leftover Lamb

Refrigerate leftover lamb in a covered container within 2 hours of cooking and use it within 3 to 4 days. Reheat slices gently, covered, with a small splash of broth to limit drying. Reheat leftovers to 165°F (75°C).

Cooked lamb can be frozen in well-sealed portions for about 2 to 3 months for best quality. Its texture may change after thawing.

Nutrition

Approximate nutrition per serving, based on 1 of 8 servings: 410 calories, 38g protein, 29g fat, and 1g carbohydrates. Approximate nutrition per 100g cooked edible lamb with the herb coating: 270 calories, 25g protein, 19g fat, and 1g carbohydrates. Values vary with the roast’s fat content and edible yield.