Reibekuchen

Reibekuchen, literally translated as "grated cakes" are also known as Kartoffelpuffer. While they are popular in all areas of Germany, they are most famous in the Rhineland, where they are also known as "Rievekooche." You'll find them being sold at street stalls, especially in Cologne, the most famous of which is situated outside the Cologne railway station.
Here's a simple recipe for potato pancakes:

Ingredients:

3 lbs potatoes
2 onions
2 eggs
salt
pepper

Preparation:

Peel and wash the potatoes. Grate potatoes and strain through a cloth. Chop onions finely and add to the potato mixture. Season mixture with pepper and salt and add eggs. Blend well. Portion mixture with small ladle and fry in hot oil on both sides until golden-brown. Serve with apple sauce.

As an easy option, you can also purchase packet mixes to make Reibekuchen.