40 g (1 1/2 oz) butter or margarine
1 medium onion, chopped
450 g (1 lb) potatoes, peeled and sliced
2 bunches watercress
600 ml (1 pt) chicken stock
425 ml (3/4 pt) yoghurt
1 egg
salt and pepper
method
1. Heat the butter, add the onion and cook until it has just softened but not browned.
2. Add the potatoes and watercress.
3. Stir and leave on a low heat for 3 minutes.
4. Add the stock and simmer for 20 minutes.
5. Mix the yoghurt with the egg.
6. When the potatoes are soft, liquidize the soup, adding the yoghurt mixture slowly.
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food-related terms, and for help on using cooking measurements, see
the measurements page.