Are you ready for a Sunday roast; or a holiday centerpiece; that’s guaranteed to be spectacular, yet requires almost no effort from you? This Slow Roast Leg of Lamb is the answer. Forget the stress of monitoring a meat thermometer, hoping for that perfect blushing pink slice. This method takes a different, utterly foolproof path: we cook a bone in leg of lamb low and slow for hours until the meat is so tender, you can pull it apart with tongs.
The secret? Roasting the lamb partially submerged in a flavorful bath of beef broth, with a bed of garlic, onion, and rosemary tucked underneath. This keeps the lean leg meat incredibly moist and infuses it with classic, savory flavor from the inside out. The reward is fall apart tender meat and a pan of juices that transform into the most incredible gravy. It’s the kind of impressive, comforting dish that feels like a special occasion, with minimal hands on work. Let’s get roasting!
Why You’ll Love This Slow Roast Lamb
- Ultra Forgiving & Foolproof: No need for a meat thermometer or precise timing. If the meat isn’t tender enough after 4.5 hours, you simply put it back in the oven until it is. This method is incredibly resilient.
- Minimal Hands On Effort: Season the lamb, arrange a few aromatics, add liquid, cover, and walk away for hours. The oven does all the work.
- Incredibly Flavorful & Moist: The slow braising in broth, along with the garlic and rosemary, ensures every bite is infused with deep flavor and remains juicy; no dry lamb here!
- The Gravy is Legendary: The cooking liquid, enriched by the lamb drippings and roasted aromatics, makes the most flavorful, savory gravy you can imagine. It’s the perfect finishing touch.
- Feeds a Crowd & Makes Amazing Leftovers: A leg of lamb is perfect for a family gathering or holiday meal. Any leftovers are fantastic for sandwiches, salads, or reheated for another easy dinner.
Let’s Make Slow Roast Leg of Lamb
This recipe is all about patience and letting time work its magic. The active prep is under 15 minutes.
Ingredients You’ll Need
For the Lamb:
- 1 (4.5 lb / 2.25 kg) bone in leg of lamb
- Kosher salt and freshly ground black pepper
- 1 ½ tablespoons olive oil
- 1 whole head of garlic, unpeeled, cut in half horizontally
- 1 yellow onion, quartered (skin on is fine)
- 2-4 fresh rosemary sprigs (2 for a whisper, 4 for a stronger flavor)
- 3 cups low sodium beef broth or stock
- 2 cups water
For the Gravy:
- 4 tablespoons all purpose flour
- 1 cup water, plus more as needed
- Salt and pepper, to taste
Step by Step Instructions
1Prep and Preheat: Preheat your oven to 335°F (170°C) for a standard oven, or 300°F (150°C) for a convection/fan oven. Place the halved garlic head, quartered onion, and rosemary sprigs in the center of a large metal roasting pan.
2Season the Lamb: Place the leg of lamb right side up (the meatier, rounder side) on top of the aromatics. Generously season all over with salt and pepper, rubbing it into the meat. Turn the lamb over so the flatter side is up and it’s mostly resting on the garlic and onion. Season this side generously as well.
3Add Liquid and Cover: Drizzle the lamb with the olive oil. Carefully pour the beef broth and 2 cups of water into the pan, around (not over) the lamb. The liquid will not cover the lamb; this is correct. It should come about halfway up the sides. Cover the entire pan tightly with aluminum foil.
4Slow Roast: Place the covered pan in the preheated oven. Roast for 4.5 hours.
5Check for Tenderness: After 4.5 hours, carefully remove the pan from the oven and take off the foil. Turn the lamb over. Test the meat by trying to pry a little piece off with a fork. It should come away very easily. If it’s still resisting, cover it back up and return it to the oven for another 30 minutes before checking again.
6Brown the Lamb: Once tender, return the uncovered pan to the oven. Roast for an additional 30-45 minutes to brown the top of the lamb beautifully.
7Rest the Meat: Transfer the lamb to a serving platter or carving board. Loosely tent it with foil. Let it rest for at least 20-30 minutes (it will stay warm for over an hour). This allows the juices to redistribute. Don’t skip this step!
Making the Perfect Gravy
8Skim the Fat: Use a large spoon to skim off and discard the excess fat that has risen to the surface of the pan juices.
9Make the Roux: Place the roasting pan directly on the stove over medium high heat. When the juices are bubbling, sprinkle the flour all over the surface. Whisk constantly for 2-3 minutes; the mixture will look thick and pasty. This cooks the raw flour taste out.
10Create the Gravy: Gradually whisk in about 1 cup of water. Continue to cook, whisking, until the gravy thickens to your desired consistency. If it gets too thick, add a splash more water. Taste and season with salt and pepper if needed (you may not need extra salt).
11Strain and Serve: For an ultra smooth gravy, strain it through a fine mesh sieve into a gravy boat or jug, pressing on the garlic, onion, and rosemary to extract every last bit of flavor.
12Serve and Enjoy: Use tongs to pull the succulent meat off the bone or carve it into chunks. Serve immediately, drenched in that incredible homemade gravy.
Serving Suggestions & Expert Tips
- The Golden Rule for Lamb Leg: Lamb leg is a lean cut. For the best results, cook it either quickly to medium rare (about 1.5 hours at high heat) or slowly until fall apart tender (this recipe). Avoid the in between zone, as it can become tough.
- Choosing Your Cut: This recipe is designed for a bone in leg of lamb, which benefits greatly from the braising liquid. You can use a boneless leg, but reduce the initial cook time by about 30 minutes and check earlier. Lamb shoulder also works wonderfully and is even more forgiving due to its higher fat content.
- Don’t Peek!: Resist the urge to open the oven during the first 4.5 hours of cooking. Keeping the foil seal intact ensures a moist, steamy environment.
- Perfect Pairings: Serve with classic sides like Crispy Roast Potatoes, buttery mashed potatoes, glazed carrots, roasted Brussels sprouts, or a fresh green salad. The gravy is excellent on everything!
- Leftovers & Storage: Store cooled meat and gravy separately in airtight containers in the refrigerator for up to 4 days. The meat reheats beautifully in the microwave with a splash of gravy or broth.
This Slow Roast Leg of Lamb is a celebration of simple, patient cooking yielding extraordinary results. I hope it becomes a cherished tradition in your home!
Ultra Tender Slow Roast Leg of Lamb
Ingredients
For the Lamb:
- 1 4.5 lb / 2.25 kg bone in leg of lamb
- Kosher salt and black pepper
- 1 ½ tbsp olive oil
- 1 whole head garlic halved horizontally
- 1 yellow onion quartered
- 2-4 sprigs fresh rosemary
- 3 cups low sodium beef broth
- 2 cups water
For the Gravy:
- 4 tbsp all purpose flour
- 1 cup water plus more as needed
- Salt and pepper to taste
Instructions
- Preheat oven to 335°F (170°C) standard or 300°F (150°C) fan.
- Place garlic, onion, and rosemary in a roasting pan. Season lamb all over with salt and pepper. Place on top of aromatics.
- Drizzle lamb with oil. Pour broth and 2 cups water around lamb (not over). Cover pan tightly with foil.
- Roast for 4.5 hours. Remove foil, turn lamb. Check tenderness with a fork. If not tender, cover and return to oven.
- When tender, return uncovered pan to oven for 30-45 mins to brown.
- Transfer lamb to platter, tent with foil, and rest for 20-30 mins.
- For Gravy: Skim fat from pan juices. Place pan on stove over medium high heat. Whisk in flour; cook 2-3 mins. Gradually whisk in 1 cup water until thickened. Season. Strain if desired.
- Pull meat apart with tongs and serve with gravy.
Notes
- Crucial: Lamb leg should be cooked either quickly to medium rare or slowly until fall apart. This slow method ensures tender, juicy meat.
- Don't Peek: Keep the foil sealed during the initial roast for best results.
- Gravy: If gravy becomes too thick, whisk in additional water. If lumpy, straining will fix it.
