Place the potatoes in a saucepan with enough lukewarm water to cover the potatoes by 1 inch. Bring to a simmer, uncovered, until the potatoes are tender and you can pierce them with a knife. Drain the potatoes and process them through a ricer or food mill into a large bowl. Alternatively, mash them as smooth as possible with a potato masher.
Combine the milk, water, butter, salt and sugar in a medium saucepan. Bring the mixture to a boil then remove from heat and add the flour all at once. Stir vigorously with a wooden spoon until the mixture forms a ball and pulls away from the sides of the pan.
Tip the dough into a large bowl or stand mixer fitting with a paddle attachement. Add the eggs, one at a time, mixing after each addition. The dough is ready when it hangs from your mixing utensil in a thicky, sticky paste. If the mixture is too firm, add an additional egg. Add the mashed potatoes and stir to combine. Season with freshly ground pepper and nutmeg.
Pour at least 4 inches of vegetable oil into a wok or large pot. Bring the oil slowly to temperature until an instant-read thermometer reads 350 F.
To form the dough into oval shape "quenelles" you'll need 2 small spoons and a cup of water to rinse them. They are shaped on eat at a time and lowered into the oil before the next one is shaped.
Take a generous spoonful of dough with a spoon and, with your free hand, hold another spoon. Holding the spoons near to the scoop end, alternate the dough from spoon to spoon, using the contour of the spoons to shape the dough into ovals. Rinse the spoons in water between each quenelle.
Carefully lower the shaped batter into the hot oil, using a spoon to release the dough from your utensil. Fry until golden brown, about 3-4 minutes, turning occasionally to cook and colour an all sides. Remove with a slotted spoon and transfer to a paper towel. Sprinkle with salt while still warm. Serve hot.