Peel the potatoes and onion. Finely grate one potato and onion into a bowl and mix well. Grate the remaining potatoes one at a time, adding the freshly grated potato to the potato and onion mixture.
Beat an egg, season with salt and add it to the potato mixture.
If you would like the outsides of the fritters to crisp add a couple of spoons of water.
Fry the fritters on a high flame in pork fat using 1tbsp of the potato mixture per fritter ...
... until golden brown on each side.
Serve immediately with sour cream, crackling or herring fillets.