Welsh Leek Soup

The leek is the national emblem of Wales. This soup is also known as Cawl Cennin in the Welsh language. 'Cawl' means broth. Leeks used to only be available from January to March, but nowadays they are available just about all year round.
Butter - 25g (1 oz)
Leeks - 700g (1½ lb)
Onions - 2 medium, chopped
Celery - 2 sticks, chopped
Chicken or vegetable stock - 1.1 litres (2 pints)
Natural yogurt - 150g (5 oz)
Chives - snipped, for garnish
METHOD

1. Melt the butter in a large pan and gently cook the leeks, onions and celery for 10 minutes until softened.
2. Add the stock and bring to the boil. Cover and simmer for 30 minutes until the vegetables are cooked.

• Liquidize. Stir in the yogurt and reheat gently without boiling. Serve    garnished with the chives.