Heat the butter in a large pan and fry the onions for 2 - 3 minutes over a medium heat, then add the leek and cook for a further 2 - 3 minutes until it starts to soften.
Add the milk and fish stock and bring to a simmer.
Put a clean tea towel over a chopping board and scrunch up the edges to catch the corn. Hold a cob upright and run a knife gently down to the base of the kernels all the way round. Repeat with the other cobs then lift the tea towel up and tip the corn into the pan.
Add the potatoes, season with salt and pepper and simmer for 8 - 10 minutes until the potato softens. Be careful not to let the milk boil or it may curdle.
If you want to mash or blend some of the chowder, do it now before adding the fish. Cut the haddock into bite sized chunks, add to the pan and cook gently for 2 minutes.
Add the prawns, lemon juice and season with black pepper. Cook for a further 1 minute then stir in the parsley and serve with bread rolls or crusty brown bread.
Use fresh sweetcorn in season or frozen or tinned or canned sweetcorn. Drain and rinse tinned sweetcorn before adding it to your chowder.
Smoked haddock is a common fish to use in a chowder, but you could use other smoked fish. Smoked Basa for example works just as well and is often cheaper.
Be careful to let your chowder simmer and not boil. Boiling may cause the milk to split and the texture may become slightly grainy.
Before adding the fish, you can blend as much of the soup as you like. Some people like to make their chowder as thick as possible and blend all the vegetables. Others prefer to leave some of the vegetables as chunks to vary the texture.
A smoked fish chowder is a meal in itself, but it is delicious served with some fresh crusty bread to mop up every last bit of the soup.
Smoked Haddock and Prawn Chowder will store in the fridge for 3 - 4 days. Place in the fridge within two hours of cooking.Freeze for up to 6 months. Leave to cool before placing in freezer bag. Leaving space at the top to allow the soup to expand. As it contains milk, it is best re-heated from frozen. Keep stirring it so the milk doesn't separate.