Boil the potatoes in their skins until tender. Drain and cool for several hours. Potatoes can also be baked, until tender.
Peel the cooked potatoes and pass them through a potato ricer or mash with a potato masher.
Mix potatoes with the eggs and the flour. Season with salt, pepper and nutmeg. Continue to knead the dough until firm.
Using your hands, shape the potato mixture into fingers. If the dough sticks to your hands, dust them with flour.
Bring water to barely a boil in a large pot. Drop small batches of the dumplings into the just simmering water. Cook until they float on the top. Remove them from the water with a slotted spoon and place them onto a plate.
Make sauerkraut:
Heat oil in a sauté pan and cook onions until soft and translucent.
Add pepper and sauerkraut and stir to combine. Cook until liquid evaporates. Remove from heat, cover and keep warm.
In another pan heat the butter and sauté the boiled dumplings until golden brown and crisp on all sides.
Add cooked dumplings to sauerkraut and toss to combine.