For four servings melt a knob of butter in a heavy based saucepan.
Add 1 chopped onion, thin strips of 2 carrots, 2 sticks celery, 1 leek and 2 diced potatoes.
Sweat vegetables for a few minutes before adding 900ml / 11⁄2 pints of fish stock and 300ml / 1⁄2 pint of milk. Season.
Bring to the boil and simmer until vegetables soften.
Skin, remove bones and cube 450g/1lb white fish – Cod, Pollock, Rock Salmon and add to vegetable base.
Continue to cook for 10 minutes.
Garnish with chopped parsley or croutons.