Gigot d’Agneau (Slow-Roasted Leg of Lamb)
Why this recipe works
- Gentle roasting: A low oven gives the bone-in lamb time to become tender without pushing the centre past a blushing finish.
- Built-in seasoning: Garlic and rosemary tucked into slits season the meat from within, while Dijon and olive oil create a savoury coating on the surface.
- Simple pan jus: White wine lifts the browned roasting juices into a quick sauce that tastes concentrated without needing a separate stock.
Get the most out of this recipe
Timing notes
- Take off the chill: Let the lamb sit out briefly before roasting so it cooks more evenly from edge to centre.
- Rest before carving: Resting allows the juices to settle, making the lamb easier to slice and keeping the meat more succulent.
- Serve warm, not rushed: Use the resting time to make the jus, then carve just before serving so the slices stay warm and moist.
Ingredient notes
- Bone-in lamb: A bone-in leg suits slow roasting well, giving a generous centrepiece with a mix of lean slices and richer, more flavourful sections.
- Dijon mustard: Dijon adds gentle sharpness and helps the oil, herbs and seasoning cling to the lamb as it roasts.
- Fresh herbs work best: Fresh rosemary is ideal here because it releases aromatic oils into the slits and stands up well to the long roast.
Common mistakes
- Skipping the thermometer: Use a meat thermometer rather than relying only on time; lamb can move from blushing to well done quickly near the end.
- Roasting too hot: A high oven can brown the outside before the centre has cooked evenly, so keep the heat gentle and cover loosely if needed.
- Carving too soon: Cutting immediately after roasting releases too much juice onto the board; rest first, then stir any collected juices into the jus.
Make-ahead tips
- Prepare the seasoning ahead: The garlic, rosemary and mustard mixture can be prepared in advance, then rubbed over the lamb before roasting.
- Freeze with jus: Leftover sliced lamb freezes best with a little jus to protect it from drying out.
- Reheat gently: Reheat covered in a 180°C (355°F) oven until piping hot, adding a little jus or pan liquid if the slices look dry.
Equipment you'll need
Ingredients
Instructions
- Heat the oven to 150°C (300°F). Pat the lamb dry, then use a small knife to make deep slits all over the surface.
- Peel and lightly crush the garlic cloves. Strip the rosemary leaves from the sprigs and finely chop them, then push the garlic and rosemary into the slits.
- Mix the Dijon mustard with the olive oil, fine sea salt and black pepper. Rub the mixture all over the lamb, including the underside, then set the lamb in a roasting pan.
- Roast for 2 hours 30 minutes to 3 hours, until the lamb is tender and a thermometer reads 55 to 60°C (130 to 140°F) for blushing. If the top is browning too quickly, loosely cover with foil for the final hour.
- Transfer the lamb to a board and rest for 20 minutes. Pour off excess fat from the roasting pan, leaving the browned juices behind.
- Set the roasting pan over a low heat on the hob, add the white wine and scrape up the sticky bits. Simmer for 3 to 5 minutes until slightly reduced, then taste and adjust with a pinch more salt and pepper if needed.
- Carve the lamb against the grain and serve with the warm jus spooned over. Any resting juices on the board can be stirred into the jus before serving.
Recipe notes
Tips
- For the most even cooking, bring the lamb out of the fridge 45 to 60 minutes before roasting so it loses its chill.
- Use a thermometer and aim for 55 to 60°C (130 to 140°F) for blushing lamb; it will rise a couple of degrees as it rests.
- If serving vulnerable groups, cook the lamb to at least 63°C (145°F) and rest well before carving.
Substitutions
- Replace Fresh rosemary with fresh thyme for a softer, more floral herb note.
- Replace White wine with dry sherry for a slightly richer, nuttier jus.
- Replace Dijon mustard with whole-grain mustard for a coarser texture and gentler heat.
Storage
- Refrigerate up to 3 days
- Cool leftovers quickly, then refrigerate in a sealed container. Freeze sliced lamb with a little jus for up to 2 months; defrost overnight in the fridge and reheat in a 180°C (355°F) oven, covered, until piping hot.
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Recipe overview
- Servings: 4 servings
- Total time: 4h (25min active)
- Difficulty: Medium
- Cuisine: French
-
Allergens:
Mustard
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