This is more Swiss than German, but Charlie (Claire’s roommate in the Claire Montrose series) likes to make them anyway.
Ingredients:
3 pounds russet potatoes (about three large)
1/2 cup snipped fresh chives or minced flat-leaf parsley
Salt and freshly ground pepper
3 tablespoons olive oil
2 tablespoons unsalted butter
Preparation:
Boil the potatoes in their jackets until just tender. Cool and store in the fridge to firm up for at least one day, preferably two. When ready to use, peel, then grate potatoes coarsely, finely chop the chives or parsley, mix together and season to taste. (Charlie says you can also add chopped bacon, to make speck rosti, though this is usually a breakfast dish.)
In a nonstick skillet combine half of the olive oil and half of the butter over medium heat; heat until quite hot. Add the potatoes, spreading them in an even layer and tamping them down with a spatula to form a compact cake. Cook for 8 minutes, or until the bottom is browned and crisp. Invert the potato cake onto a plate.
Add the remaining oil and butter to the skillet, slide the potato cake, cooked side up, into the hot fat and cook another 8 minutes, or until the underside is browned and crisp. Slide the cake onto a plate and cut into wedges. Serve immediately.