Remove the peel from the potatoes, grate finely. Mash the onions completely on the star wheel and mix into the potatoes on the spot.
If the potatoes give off a lot of water, pour it off. Add the egg to the grated potatoes, season with salt and pepper. Work the dough on the spot if possible: Spread a dab of batter in the hot oil on each side and bake until crispy on both sides. Drain on kitchen roll before serving.