Cullen skink soup
Put the haddock fillet in a large frying pan and cover with boiling water. Let stand for 10 minutes, then drain, reserving 300ml/10fl oz of the soaking water. Flake the fish, taking care to remove all the bones.
Melt the butter in a large saucepan over a low heat. Add the onion and sweat gently for 10 minutes until softened. Add the milk and bring to a gentle simmer before adding the potatoes. Cook for 10 minutes.
Add the reserved haddock flakes and the cod. Simmer for a further 10 minutes until the cod is tender.
Remove about one-third of the fish and potatoes, put in a blender or food processor and purée until smooth. Return to the soup with the cream, parsley and salt and pepper to taste. Add a little of the reserved soaking water if the soup seems too thick. Reheat gently and serve hot.