Serves 4

900 g (2 lb) boned shoulder of lamb

15 ml (1 tbsp) olive oil

40 g (1 1/2 oz) butter

1 Spanish onion, thinly sliced

550 g (1 1/4 lb) very starchy potatoes, sliced

salt and ground black pepper

bouquet garni

2 leeks, washed and sliced

about 2.3 (4 pt) boiling water

8 small potatoes, trimmed into regular, oval shapes

16 white button onions, blanched

30 ml (2 tbsp) caster sugar

30 ml (2 tbsp) finely chopped parsley

Worcestershire sauce, to serve

1. Cut the lamb into squares weighing about 50 g (2 oz) each, discarding any fat or gristle. In a large flameproof casserole, heat the olive oil and 15 g (1/2 oz) butter. Add enough meat to cover the base and saute until evenly browned all over, then remove with a slotted spoon and reserve. Repeat with the remaining lamb.

2. In the casserole, arrange alternate layers of lamb, sliced onion and sliced potatoes, seasoning to taste with salt  and freshly ground black pepper between each layer. Add the bouquet garni, the sliced leek and sufficient boiling water to cover. Bring to the boil, cover and simmer for 30 minutes.

3. With a slotted spoon, remove the meat and reserve. Allow to cool a little, then puree the  vegetables  and  cooking  juices  in  a blender, in batches if necessary.

4. Return to the casserole and boil rapidly for about 45 minutes, or until reduced to 1.4 L (2 1/2 pt) of liquid.

5. Add the trimmed potatoes and simmer for  a  further  20-30  minutes,  or  until potatoes are cooked but not too soft.

6. While the potatoes are cooking, heat the remaining butter in a medium-sized saucepan. Add the onions, sugar and 150 ml (5 fl oz) water, then simmer for 15 minutes, or until the onions are caramelized and tender, turning frequently with a wooden spoon.

7. When the potatoes are cooked, return the  meat  to  the casserole and  add the caramelized onions and their juices. Reheat very gently over a low heat until the meat is hot (reheating over a high heat tends to toughen it).

8. Transfer to a heated deep serving dish. Sprinkle with chopped parsley and serve with Worcestershire sauce.