Serves 6 - 8

1.8 kg (4 lb) leg of lamb

freshly ground black pepper

2 garlic cloves, finely chopped

60 ml (4 tbsp) Dijon mustard

5 ml (1 tsp) ground ginger

20 ml (4 tsp) soy sauce

30 ml (2 tbsp) olive oil

salt

2 bunches of watercress

1. Using a sharp knife, carefully remove the   lamb's   outer   skin.   Discard.   Season generously with ground black pepper.

2. In a bowl, combine the finely chopped garlic, Dijon mustard, ground ginger and soy sauce. Stir until well blended with a fork or small wire whisk, then beat in the olive oil drop by drop.

3. Place the lamb on a rack in a roasting tin. Brush the mustard mixture all over the meat. Cover and leave to marinate for 4 hours in a cool place.

4. Heat the oven to 170C (325F) gas 3.

5. Just  before cooking, season the lamb generously with salt.

6. Cook the lamb in the oven for 1 hour 30 minutes for pink meat, or 1 hour 45 minutes for well-done lamb. Turn the lamb twice during cooking, so that it is browned evenly all over. This will also prevent the mustard coating from forming a brown crust.

7. Transfer the roast lamb to a heated dish and leave in a warm place for 10 - 15 minutes to settle before carving.

8. Meanwhile, wash the watercress in cold water, removing and discarding the stems. Drain and pat dry with a clean tea-towel or absorbent paper.

9. To serve, make a bed of watercress leaves on a heated serving dish and lay the Mustard roast leg of lamb on top.