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Roast lamb with caramelised onions recipe

Roast lamb with caramelised onions recipe

12 ratings

This fabulous lamb roast is complemented by the addition of sweet caramelised onions. Serve with a zesty gremolata for a gorgeous vibrant centrepiece. See method

  • Serves 6
  • 10 mins to prepare and 1 hr 45 mins to cook
  • 575 calories / serving
  • Gluten-free


  • 2·5kg leg of lamb (bone in)
  • 15g butter
  • 3 onions, finely sliced
  • 3 garlic cloves, chopped
  • 1 tbsp balsamic vinegar
  • 200ml white wine
  • 2 sprigs fresh thyme
  • 3 sprigs fresh rosemary
  • 300ml hot lamb stock

For the gremolata

  • 1 lemon, zested
  • 1 garlic clove
  • handful flat-leaf parsley
  • 1 sprig rosemary, leaves only

Each serving contains

  • Energy

  • Fat

    42g 60%
  • Saturates

    21g 105%
  • Sugars

    5g 6%
  • Salt

    1.3g 22%

of the reference intake
Carbohydrate 7.3g Protein 38.7g Fibre 1.6g


  1. Preheat the oven to gas 7, 220°C, fan 200°C. Drizzle a little oil over the lamb, and season. Put in a roasting tray and cook for 20 mins.
  2. Heat the butter and the remaining oil in a wide pan. Fry the onion until soft and golden. Add the garlic and fry for 1 min. Add the vinegar and let it bubble. Stir in the wine, thyme and rosemary, and simmer for 1-2 mins more. Put the onions around the lamb, pour in the stock, and cover the tray with foil.
  3. Reduce the oven to gas 6, 200°C, fan 180°C and roast the lamb for 15 mins per 500g – 1 hour and 15 mins for a 2.5kg leg. The lamb will be just pink in the middle. For well-done meat, roast for 20 mins per 500g. Baste the lamb with the cooking juices a few times during cooking, and then transfer to a serving plate to rest for 20 mins.
  4. To make the gremolata, use a potato peeler to remove the peel from the lemon. In the middle of a chopping board, cut the peel into thin strips, top with the garlic, parsley and rosemary and finely chop everything together. Season, place in a dish and set aside.
  5. Serve the lamb with the onions and gremolata.

See more Lamb recipes

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