1 tbsp unsalted butter
1 medium onion
400g medium potatoes (about 2), peeled and cut into 1cm cubes
250g smoked haddock
250ml whole milk
½ small bunch of parsley, stems removed and coarsely chopped, leaves finely chopped
1 bay leaf
Melt the butter in a saucepan over a medium heat, then add the onion and fry for 5-8m until translucent but not browned. Add the potatoes and 300ml water and bring to the boil. Reduce the heat slightly and simmer for 10-15m.
Meanwhile, put the haddock in another pan and cover with the the milk. Add the parsley stems and bay leaf to the milk. Cook gently for 5m, or until just tender. Remove the haddock from the milk with a slotted spoon (reserving the milk) and transfer to a plate and leave to cool slightly. When cool enough to touch, flake into large pieces, removing any bones.
Strain the bay leaf and parsley stems from the reserved milk and add it along with the flaked haddock to the pan with the potato mixture and cook for another 5m.
Season with freshly ground pepper and sprinkle over the parsley leaves to serve.