450g/1lb Jerusalem artichokes, peeled and cut into chunks
2 carrots, peeled and chopped
½ bulb garlic, chopped
1 leek, chopped
½ lemon
1 onion, peeled and chopped
3 tbsp fresh parsley, roughly chopped
300²µ/10½´Ç³ú purple sprouting broccoli, boiled until just tender
1 sprig fresh rosemary
3 tbsp capers, rinsed and drained
salt and freshly ground black pepper
pinch freshly ground nutmeg
1 tbsp olive oil
1.25 litres/2½ pints chicken stock, or vegetable stock, warmed
25g/1oz butter
2 tbsp double cream
25ml/1fl oz double cream
1.25kg/2½lb breast of lamb, taken off the bone, rolled and tied (you can ask your butcher to do this for you)