This Costco Leg of Lamb Recipe is a juicy and tender recipe, which is seared under the broiler and then slow-roasted with garlic and rosemary. It’s the perfect centerpiece for a holiday dinner, ready in about 2 hours.
Jump to RecipeCostco Leg of Lamb Recipe Ingredients
- 1 (5 to 7 pound) bone-in leg of lamb
- 3 tablespoons olive oil
- Kosher salt
- Freshly ground black pepper
- 6 cloves garlic, minced
- Leaves from 3 fresh rosemary sprigs, coarsely chopped (about 1 tablespoon)
How To Make Costco Leg of Lamb
- Prepare the lamb: Take the leg of lamb out of the refrigerator about an hour before cooking to let it come to room temperature. This helps it cook more evenly. Place the lamb on a rack inside a roasting pan. Drizzle with olive oil and rub it all over the meat. Season generously on all sides with salt and pepper.
- Broil the lamb: Arrange an oven rack so the top of the lamb is a few inches from the broiler element and preheat the broiler. Place the lamb under the broiler, fat-side down, and broil for about 5 minutes, until the surface is seared and browned. Flip the leg over and broil the other side for another 5 minutes.
- Season and prepare for roasting: Remove the lamb from the oven. Turn off the broiler and set the oven temperature to 325°F. Reposition the oven rack to the middle of the oven. Rub the minced garlic and chopped fresh rosemary all over the top (fat side) of the lamb.
- Roast the lamb: Tent the pan loosely with aluminum foil to prevent the garlic and rosemary from burning. Place the lamb back in the oven and roast for 1 hour.
- Check for doneness: After an hour, remove the foil and check the internal temperature with an instant-read thermometer inserted into the thickest part of the meat, not touching the bone. For a perfect medium-rare, remove the lamb from the oven when it reaches 135°F.
- Continue cooking if needed: If the lamb is not yet at your desired temperature, continue cooking it uncovered, checking the temperature every 20 minutes.
- Rest the meat: Once the lamb reaches your target temperature, transfer it to a cutting board and let it rest for at least 15 minutes before carving.
- Carve and serve: Carve the lamb against the grain into slices and arrange on a platter to serve.
Recipe Tips
- Why bring the lamb to room temperature? Letting the lamb sit out for an hour before cooking ensures that it cooks more evenly from edge to center. A cold roast can result in an overcooked exterior and an undercooked interior.
- Why broil the lamb first? The initial high heat of the broiler creates a delicious, deeply browned crust on the outside of the lamb, searing in the juices and adding a huge amount of flavor.
- Why is resting the meat so important? Resting the lamb for at least 15 minutes before slicing is crucial. It allows the juices to redistribute throughout the meat, ensuring that every bite is moist and flavorful instead of running out onto the cutting board.
- How to get the perfect temperature: A reliable instant-read meat thermometer is the best tool for cooking a large roast perfectly. It takes all the guesswork out of the process.
What To Serve With Leg of Lamb
This impressive main course pairs beautifully with classic roast dinner sides.
- Creamy mashed potatoes or garlic-rosemary roasted potatoes
- Mint pesto or a traditional mint jelly
- Sautéed green beans with almonds or roasted asparagus
- A simple pan gravy made from the drippings in the roasting pan
How To Store Leg of Lamb
Refrigerate: Store any leftover sliced lamb in an airtight container in the refrigerator for up to 3 days. Freeze: For best results, freeze leftover rare to medium-rare lamb in slices, wrapped tightly in foil. To reheat, place the frozen, foil-wrapped slices in a 350°F oven until warmed through.
Costco Leg of Lamb Nutrition Facts
- Calories: 450kcal
- Carbohydrates: 2g
- Protein: 45g
- Fat: 28g
- Saturated Fat: 10g
- Sodium: 250mg
- Fiber: <1g
- Sugar: 0g
Nutrition information is estimated per serving and may vary based on specific ingredients and portion sizes.
FAQs
This is a popular and classic method for preparing the beautiful bone-in leg of lamb roasts often sold at Costco. While not an “official” recipe from their bakery, it’s a perfect way to cook their product.
It depends on your preference. Use this guide:
Rare: 125-130°F
Medium-Rare: 135°F (recommended)
Medium: 140-145°F
Well-Done: 155°F+ Remember that the temperature will rise a few degrees as the lamb rests.
Yes, but the cooking time will be shorter. A boneless leg of lamb will cook more quickly, so start checking the internal temperature earlier, after about 45 minutes of roasting time.
Try More Recipes:
Costco Leg of Lamb Recipe
Course: DinnerCuisine: AmericanDifficulty: Easy10
servings15
minutes1
hour30
minutes450
kcalA classic and foolproof method for a garlic and rosemary roasted bone-in leg of lamb, resulting in a juicy, tender, and flavorful centerpiece.
Ingredients
1 (5-7 lb) bone-in leg of lamb
3 tbsp olive oil
Kosher salt and black pepper
6 cloves garlic, minced
1 tbsp fresh rosemary, chopped
Directions
- Let the lamb sit at room temperature for 1 hour. Preheat the broiler.
- Rub the lamb with olive oil, salt, and pepper. Broil for 5 minutes on each side until browned.
- Turn off the broiler and set the oven to 325°F.
- Rub the top of the lamb with minced garlic and chopped rosemary.
- Tent with foil and roast for 1 hour.
- Remove the foil and continue to roast until the internal temperature reaches 135°F for medium-rare.
- Let the roast rest for at least 15 minutes before carving and serving.
Notes
- Bringing the lamb to room temperature before cooking is key for even results.
- The initial broiling step creates a delicious, flavorful crust.
- Resting the meat before slicing is a crucial step to keep it juicy.
- Use a meat thermometer for the most accurate way to check for doneness.
