Place the flour, eggs, milk, salt and pepper in a bowl, and whisk until smooth. Let rest for a few minutes.

Finely grate the potatoes and onion into the bowl, and mix with a spatula.

Heat a non-stick skillet over medium heat. Melt a small piece of butter, then ladle in some batter to form a 10 cm disc. Cook until golden brown on both sides, transfer to an oven-proof dish, and top with another small piece of butter. Repeat until you run out of batter.

Cover with foil, and bake in a 175⁰ C oven for about 5 minutes. Serve hot, with sour cream on the side.