Melt the butter in a large pan. Add leeks, potatoes and celery. Cook over a low heat for 5
minutes, blend in water and seasoning. Bring to the boil. Reduce heat and simmer for 10
minutes or until potatoes are almost tender. Check the fish for bones and cut
into 2.5cm pieces. Stir into the soup. Continue simmering gently for
about 5 minutes or until the fish is tender. Serve hot sprinkled with dill.