Roast Lamb with Fennel and Mustard Butter Roast Lamb with Fennel and Mustard Butter

Roast Lamb with Fennel and Mustard Butter

A flavourful addition to the Sunday roast. Half lamb leg with a mustard, fennel seed and garlic butter

prep time
5 mins

cook time
1 hour 30 minutes

4 people

To Cook Medium: 25 minutes per 450g/1lb plus 25 minutes

To Cook Well Done: 30 minutes per 450g/1lb plus 30 minutes


  • 900g-1.3kg/2-3lb lean lamb half leg joint
  • Salt and freshly milled black pepper
  • For the fennel and mustard butter

  • :50g/2oz softened butter
  • 15-30ml/1-2tbsp wholegrain mustard
  • 45ml/3tbsp fennel seeds, finely crushed
  • 2 garlic cloves, peeled and finely chopped
  • 30ml/2tbsp freshly chopped flat-leaf parsley


  1. Prepare the fennel and mustard butter; in a small bowl mix all the ingredients together.
  2. Preheat the oven to Gas mark 4-5, 180-190°C, 350-375°F.
  3. Place the joint on a chopping board and make several slits over the surface. Season and spread the butter over the joint and into the slits.
  4. Place on a metal rack in a large non-stick roasting tin and open roast in a preheated oven for the preferred, calculated cooking time, basting with any rich meat juices.
  5. Slice the lamb and serve with a light rice salad.


The flavoured butter can be used with lamb steaks too. Wrap any leftover butter in cling film and freeze for up to 2 months.