Quick Recipe Version (TL;DR)

Yield: 6–8 servings
Prep Time: 25 minutes (plus optional 1–24 hours marinating)
Cook Time: 1 hour 45 minutes
Total Time: 2 hours 15 minutes (plus optional marinating time)

Quick Ingredients

1 bone-in leg of lamb, 4–5 lb (1.8–2.3 kg)
2 ½ tsp kosher salt, divided (plus more to taste)
1 ½ tsp freshly ground black pepper, divided
8 cloves garlic
3 Tbsp fresh rosemary leaves
2 tsp fresh thyme leaves (or 1 tsp dried)
1 lemon (zest + 2 Tbsp juice)
5 Tbsp olive oil, divided
2 lb (900 g) mixed root vegetables (carrots, parsnips, potatoes, etc.)
1 large red onion
1 cup (240 ml) low-sodium chicken or beef stock
½ cup (120 ml) dry red wine (or extra stock)
2 Tbsp unsalted butter (for the jus)

Do This

1. Pat lamb dry, trim excess fat, and let sit at room temperature for 45–60 minutes. Preheat oven to 425°F (220°C).
2. Blitz or mash garlic, rosemary, thyme, lemon zest, 2 tsp salt, 1 tsp pepper, and 3 Tbsp olive oil into a paste. Rub all over lamb; marinate if time allows.
3. Toss chopped root vegetables and onion with 2 Tbsp olive oil, ½ tsp salt, and ½ tsp pepper. Spread on a large roasting pan.
4. Place lamb on a rack over the vegetables. Roast 15 minutes at 425°F (220°C), then reduce to 350°F (175°C) and roast 1–1¼ hours more, until 130–135°F (54–57°C) for medium-rare.
5. Transfer lamb to a board, tent loosely with foil, and rest 20–25 minutes. Keep vegetables warm.
6. Make pan jus: pour off excess fat, deglaze pan with wine, add stock, simmer to reduce, then whisk in butter.
7. Slice lamb against the grain, serve with caramelized root vegetables, and spoon warm pan jus over the top.

Why You’ll Love This Recipe

A classic garlic-and-rosemary crust gives the lamb deep, savory flavor without any tricky techniques.
Everything roasts in essentially one pan, giving you tender meat, caramelized vegetables, and a rich jus all at once.
Perfect for special occasions, but simple and reliable enough for confident weekend cooking.
Includes clear temperatures, times, and tips so you can hit perfect doneness even if it is your first time roasting lamb.

Grocery List

Produce: 1 leg of lamb (from the meat counter), garlic, fresh rosemary, fresh thyme, 1 lemon, carrots, parsnips, potatoes (Yukon Gold or red), red onion, optional fresh parsley for garnish.
Dairy: Unsalted butter.
Pantry: Olive oil, kosher salt, black pepper, low-sodium chicken or beef stock, dry red wine (or extra stock), optional Dijon mustard and honey (for a slightly sweeter jus).

Full Ingredients

For the Roast Leg of Lamb

1 bone-in leg of lamb, 4–5 lb (1.8–2.3 kg), trimmed of excess surface fat and silverskin
2 tsp kosher salt (for seasoning the meat directly)
1 tsp freshly ground black pepper

For the Garlic-and-Rosemary Crust

8 large cloves garlic, roughly chopped
3 Tbsp fresh rosemary leaves (about 3–4 sprigs, stripped from stems)
2 tsp fresh thyme leaves (or 1 tsp dried thyme)
Zest of 1 lemon (about 1 tsp packed zest)
2 Tbsp freshly squeezed lemon juice
3 Tbsp extra-virgin olive oil
½ tsp kosher salt
½ tsp freshly ground black pepper

For the Caramelized Root Vegetables

1 lb (450 g) carrots, peeled and cut into 1 ½-inch (4 cm) chunks
8 oz (225 g) parsnips, peeled and cut into 1 ½-inch (4 cm) chunks
12 oz (340 g) baby potatoes or Yukon Gold potatoes, halved if large
1 large red onion, peeled and cut into thick wedges
2 Tbsp extra-virgin olive oil
1 tsp kosher salt
½ tsp freshly ground black pepper
2–3 fresh rosemary sprigs (left whole, for roasting with the vegetables)

For the Rich Pan Jus

½ cup (120 ml) dry red wine (such as Cabernet Sauvignon, Merlot, or Côtes du Rhône), or use extra stock
1 cup (240 ml) low-sodium chicken or beef stock
1 tsp Dijon mustard (optional, for gentle tang)
1 tsp honey or sugar (optional, to balance acidity)
2 Tbsp unsalted butter, chilled and cut into small cubes
Salt and pepper, to taste

For Serving (Optional)

Fresh rosemary or thyme sprigs, for garnish
Flaky sea salt, for sprinkling
Lemon wedges, for squeezing at the table

Step-by-Step Instructions

Step 1: Bring the Lamb to Room Temperature and Prep the Pan

Remove the leg of lamb from the refrigerator 45–60 minutes before cooking. Pat it very dry with paper towels; dry meat browns better. Trim off any thick, hard layers of surface fat and visible silverskin, but leave a thin, even layer of fat for flavor and moisture. Sprinkle the lamb all over with 2 tsp kosher salt and 1 tsp black pepper, pressing gently so the seasoning adheres. Set aside at room temperature.

Meanwhile, preheat your oven to 425°F (220°C) with a rack in the lower-middle position. Choose a large, sturdy roasting pan with at least 2-inch (5 cm) high sides. If you have a roasting rack that fits inside, set it aside for now; you will place it over the vegetables later.

Step 2: Make the Garlic-and-Rosemary Crust

In a mini food processor, mortar and pestle, or on a cutting board with a chef’s knife, combine the chopped garlic, rosemary leaves, thyme, and lemon zest. Process or finely chop until the mixture is very small and fragrant. Add the lemon juice, 3 Tbsp olive oil, ½ tsp kosher salt, and ½ tsp black pepper, and mix into a loose paste.

Place the lamb on a cutting board. If there are very thick areas, you can make a few shallow slashes (about ½ inch / 1.25 cm deep) in the thickest parts to help the seasoning penetrate and the meat cook more evenly. Rub the garlic-rosemary paste all over the lamb, pressing some into any slashes and folds. If time allows, cover and refrigerate for 1–24 hours for deeper flavor; bring back to room temperature before roasting.

Step 3: Prep the Caramelized Root Vegetables

In the roasting pan, combine the carrots, parsnips, potatoes, and red onion wedges. Drizzle with 2 Tbsp olive oil and sprinkle with 1 tsp kosher salt and ½ tsp black pepper. Toss well so every piece is coated. Scatter the rosemary sprigs over the vegetables.

Spread the vegetables into an even layer, leaving a space in the center if your lamb will sit directly on them, or position a roasting rack over the vegetables if using one. The vegetables will roast in the flavorful drippings from the lamb, becoming caramelized and tender.

Step 4: Sear the Lamb at High Heat

Place the lamb (on the rack or directly on top of the vegetables) in the preheated 425°F (220°C) oven. Roast for 15 minutes. This initial blast of high heat helps set the crust and start browning the outside of the meat.

After 15 minutes, without opening the oven for too long, reduce the oven temperature to 350°F (175°C). Continue roasting until the lamb reaches your desired internal temperature. For medium-rare, aim for 130–135°F (54–57°C) in the thickest part of the meat, which will take about 60–75 minutes more for a 4–5 lb (1.8–2.3 kg) leg. Start checking with an instant-read thermometer after 50–55 minutes at 350°F, inserting the probe into the thickest part away from the bone.

Step 5: Finish Roasting and Rest the Lamb

While the lamb roasts at 350°F (175°C), stir the vegetables once or twice so they brown evenly and absorb the pan juices. If they begin to look too dark before the lamb is done, loosely tent just the vegetable area with a strip of foil, or move the pan to a slightly higher oven rack.

When the lamb reaches your target temperature (for reference: 125–130°F / 52–54°C for rare; 130–135°F / 54–57°C for medium-rare; 140–145°F / 60–63°C for medium), transfer it to a large cutting board. Tent loosely with foil and let it rest for 20–25 minutes. The internal temperature will rise a few degrees as it rests, and the juices will redistribute, giving you moist slices.

Keep the vegetables in the turned-off oven with the door cracked open to stay warm, or transfer to a warm serving dish and cover.

Step 6: Make the Rich Pan Jus

Place the roasting pan over medium heat on the stovetop (use two burners if needed). If there is a thick layer of fat on top of the pan juices, spoon off most of it, leaving about 1–2 Tbsp in the pan for flavor. Be sure not to discard the browned bits stuck to the bottom; those are key to the jus.

Pour in the red wine (or an extra ½ cup / 120 ml stock if not using wine) and bring to a simmer, scraping up all the browned bits with a wooden spoon. Let the wine reduce by about half, 3–4 minutes. Add the 1 cup (240 ml) stock and simmer another 5–7 minutes, until slightly reduced and flavorful.

Whisk in the Dijon mustard and honey, if using, and taste. Adjust with salt and pepper as needed. Turn off the heat and whisk in the cold butter, a few cubes at a time, until melted and the jus is glossy and slightly thickened. If you prefer a very smooth jus, strain it through a fine-mesh sieve into a small saucepan or serving jug and keep warm.

Step 7: Slice and Serve

Remove the foil from the rested lamb. Using a sharp carving knife, slice thin or thick pieces against the grain for maximum tenderness. For a bone-in leg, it often helps to first cut large chunks away from the bone, then slice those pieces crosswise into neat slices.

Arrange the caramelized root vegetables on a warm serving platter. Fan the sliced lamb over or alongside the vegetables. Spoon some of the warm pan jus over the lamb and around the platter, reserving extra in a small jug at the table. Garnish with fresh rosemary or thyme sprigs and a sprinkle of flaky sea salt if desired. Serve immediately, with lemon wedges on the side for a bright finishing squeeze.

Pro Tips

Use a thermometer. Lamb can go from perfect to overcooked quickly. An instant-read thermometer is the easiest way to hit your preferred doneness.
Do not skip the resting time. Resting allows the juices to redistribute so they do not run all over the cutting board. This alone can make the difference between dry and succulent meat.
Cut vegetables to similar size. Aim for roughly 1 ½-inch (4 cm) chunks so carrots, parsnips, and potatoes cook at a similar rate and caramelize evenly.
Adjust jus intensity. If the jus tastes too sharp, add a splash more stock or a tiny bit of honey. If it is too mild, simmer a bit longer to reduce and concentrate the flavor.
Prep ahead for easy entertaining. You can trim the lamb and prepare the garlic-herb paste a day ahead, keeping them chilled separately, then rub the paste on 1–24 hours before roasting.

Variations

Greek-inspired lemon-herb lamb: Add 1 tsp dried oregano and ½ tsp ground cumin to the garlic-rosemary paste, and serve with lemon wedges and a side of tzatziki or Greek yogurt.
Spiced lamb with root vegetables: Add 1 tsp smoked paprika and ½ tsp ground coriander to the crust. Toss the vegetables with a pinch of cumin and paprika before roasting for a warmer, earthier flavor profile.
Boneless leg of lamb: This recipe works beautifully with a 3–4 lb (1.4–1.8 kg) boneless, netted leg. Cooking time will be slightly shorter; start checking internal temperature after 45 minutes at 350°F (175°C).

Storage & Make-Ahead

Leftover lamb will keep, tightly covered, in the refrigerator for up to 3–4 days. Store the meat, vegetables, and jus separately for best results. Reheat the lamb gently, either in a covered dish in a 275°F (135°C) oven until just warmed through, or in slices, briefly, in a covered skillet with a splash of stock or jus to keep it moist. The vegetables can be reheated on a baking sheet at 350°F (175°C) until hot and re-crisped at the edges.

For longer storage, sliced lamb can be frozen in an airtight container or freezer bag for up to 2–3 months. Thaw overnight in the refrigerator before reheating. You can also make the garlic-herb paste up to 2 days ahead and refrigerate it, and you can peel and cut the root vegetables a few hours in advance, storing them in cold water (drain and dry well before roasting).

Nutrition (per serving)

Approximate values for 1 of 8 servings (including vegetables and jus): about 650 calories; 38 g protein; 40 g fat (15 g saturated); 22 g carbohydrates; 4 g fiber; 5 g sugar; 860 mg sodium. Actual values will vary based on the exact size of the lamb leg, trimming, and how much fat is removed from the pan before making the jus.

Garlic Rosemary Roast Leg of Lamb With Root Vegetables