Peel and rinse the potatoes, then cut them into pieces.

Fill a pot with water and salt, and heat it on the stove. When the water is warm, add the fish. Once the fish is cooked, remove it and add the potatoes. Cook until the potatoes are tender.

Remove most of the water from the pot with the potatoes, leaving just the potatoes behind. Add the flaked fish to the potatoes. Thin the mayonnaise by mixing in a little of the reserved cooking water until it is quite runny, then gradually pour the mayonnaise over the potatoes while stirring constantly over low heat until well heated. Serve and enjoy.

To make the mayonnaise: Place the 2 eggs, the cup of oil, a little salt, and a splash of lemon juice in a blender cup. Place the blender at the bottom and blend without lifting it until the mayonnaise thickens. Set aside.