3 sticks celery, finely chopped
1 leek, halved lengthways and thinly sliced
2 large onions, finely chopped
250g/9oz potatoes, peeled and finely chopped
150g/5oz savoy cabbage
400g/14oz can Italian chopped tomatoes
2 tbsp green basil pesto
salt and freshly ground black pepper
3 tbsp olive oil
2 litres/3Β½ pints beef or vegetable stock
40²µ/1Β½΄Η³ϊ butter