Flake the smokie and add to the water and bring to the boil. Remove from heat immediately and allow to cool for 10 minutes.
Remove the fish with slotted spoon and keep aside. Add the potatoes, onions, turmeric and cayenne the water and boil for until the potatoes are tender, about 20 minutes. Mash the potatoes and onions together with a fork and blend in the milk and butter.
Gently stir in the smokie and bring back to a heat.