Name: Hairy Bikers Slow Roast Leg of Lamb Recipe
Prep time: 20 min
Cook time: 5 h
Total time: 5 h 40 min
Ingredients: 1 leg of lamb, bone-in (approx. 2.5kg); 4 cloves garlic, sliced; 4 sprigs of fresh rosemary; 2 tablespoons olive oil; Salt and pepper; 2 large onions, chopped; 2 carrots, chopped; 2 celery stalks, chopped; 250ml red wine; 750ml beef or lamb stock

This tender slow roast leg of lamb is made with garlic, rosemary, red wine and beef stock. Roasted low and slow for 4 to 5 hours, the meat falls off the bone. It serves 6 and takes about 20 minutes to prepare.

I make this every time we have a family gathering or a special Sunday lunch. The smell of lamb and rosemary filling the kitchen is one of my favourite things about cooking.

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Slow Roast Leg of Lamb Ingredients

For the Lamb:

1 leg of lamb, bone-in (approx. 2.5kg)
4 cloves garlic, peeled and sliced
4 sprigs of fresh rosemary
2 tablespoons olive oil
Salt and freshly ground black pepper

For the Gravy:

2 large onions, roughly chopped
2 carrots, roughly chopped
2 celery stalks, roughly chopped
250ml red wine
750ml beef or lamb stock
1 tablespoon plain flour (optional, for thickening)

How To Make Slow Roast Leg of Lamb

Prepare the lamb: Preheat your oven to 160°C (140°C Fan / Gas Mark 3). Make small incisions all over the leg and push garlic slices and rosemary pieces into the cuts. Rub with olive oil and season generously with salt and pepper.
Sear the meat: Place a large flameproof roasting tin on the hob over high heat. Sear the lamb on all sides until nicely browned. This creates a rich, flavourful crust.
Cook the vegetables: Remove the lamb and set aside. Add the onions, carrots and celery to the tin. Cook for 5 to 7 minutes, stirring occasionally, until softened and lightly browned.
Deglaze and add liquid: Pour the red wine into the tin and scrape up the browned bits with a wooden spoon. Let the wine bubble and reduce by half, then pour in the stock.
Roast the lamb: Place the seared lamb back on top of the vegetables and liquid. Cover the tin tightly with a double layer of aluminium foil. Roast for 4 to 5 hours until the meat is completely tender and falling away from the bone.
Rest the meat: Remove the lamb and place on a warm platter. Cover loosely with foil and rest for at least 20 minutes before carving.
Make the gravy: Strain the liquid through a sieve into a saucepan, pressing the vegetables to extract all the juice. Skim off any excess fat and simmer until reduced. For a thicker gravy, whisk in a paste of flour and cold water, then season to taste.
Serve: Carve or pull the tender lamb from the bone and serve with the hot gravy.

What Is the Secret to Perfect Slow Roast Leg of Lamb?

Bring it to room temperature: Take the lamb out of the fridge about an hour before cooking. This helps it cook more evenly throughout.
Always sear first: Browning the lamb in a hot pan before roasting builds deep flavour. It creates a rich crust that improves both the meat and the gravy.
Seal it tightly: Trapping the steam in the roasting tin is the key to tender results. A tight double layer of foil ensures the lamb braises gently in the liquid.
Rest before carving: Let the lamb rest for at least 20 minutes after cooking. This allows the juices to redistribute, keeping every slice moist and full of flavour.
Save the leftovers: Any leftover lamb works brilliantly in a leftover lamb shepherd’s pie. Simply shred the meat and fold it into the filling.

What Should You Serve on the Side?

This slow roast lamb is the star of a classic Sunday roast. Serve it with crispy roast potatoes, creamy mashed potatoes or a rich dauphinoise for something special.

For vegetables, honey-glazed carrots and parsnips, steamed green beans or braised cabbage all pair well. A sharp mint sauce on the side finishes the plate perfectly.

Does This Keep Well?

Store leftover lamb and gravy in separate airtight containers in the fridge for up to 3 days. Reheat gently in the oven or microwave, adding a splash of gravy to keep the meat moist.

Sliced lamb also freezes well. Wrap tightly in cling film and then foil, or use a freezer bag. Store the gravy in a separate container.

Both will keep in the freezer for up to 3 months. Thaw overnight in the fridge before reheating.

Nutrition Facts

Serving Size: 1 serving (approx. 200g of lamb)

Calories: 580 kcal
Total Fat: 35g
Saturated Fat: 15g
Cholesterol: 190mg
Sodium: 450mg
Total Carbohydrate: 8g
Dietary Fibre: 2g
Sugars: 4g
Protein: 55g

Frequently Asked Questions

How long does slow roast leg of lamb take to cook? A 2.5kg bone-in leg of lamb needs 4 to 5 hours at 160°C (140°C Fan / Gas Mark 3). The meat is ready when it pulls easily from the bone with a fork.

What temperature is best for slow roasting a leg of lamb? A low oven at 160°C (140°C Fan / Gas Mark 3) is ideal. This gentle heat breaks down the connective tissue slowly, giving you tender meat without drying it out.

How does Hairy Bikers slow roast leg of lamb compare to other recipes? Many slow roast lamb recipes from sites like RecipeTin Eats and BBC Good Food use similar temperatures. This version stands out with its red wine and stock braising liquid, which creates a rich built-in gravy.

Can I use a boneless leg of lamb instead? You can, but the bone adds flavour and helps keep the meat moist during the long cook. If using boneless, reduce the cooking time by about 45 minutes and check earlier.

What other lamb recipes work well for a slow cook? If you enjoy slow-cooked lamb, try Hairy Bikers lamb shanks for a smaller cut that is just as tender. Shanks cook in about half the time and make a great midweek meal.

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