Boil the unpeeled potatoes until semi-tender the day before preparation (very important!).
Peel and grate, using a grater with fairly large holes. Heat the butter in a skillet. Add the potatoes and sprinkle with salt. Using a spatula, press into a round loaf.
Sprinkle with milk and cover securely (cover with a soup bowl or a tightly fitting lid). Reduce the heat as soon as the potatoes begin to sizzle. Fry very slowly for another 30 minutes. Rösti must not be stirred, otherwise they will not form a crust. During this time a brown crust will form. Cover the pan with a flat platter and flip the Rösti onto it.
Variations:
Rösti can also be prepared from raw, finely grated potatoes. Turn a few time in hot butter, then press into a loaf and cover. Fry for 15 to 20min.
Rösti with Bacon: Finely chop lean bacon and sauté in butter. Add to potatoes.
Rösti with Onions: Cut onions into strips. Fry with the potatoes.
Rösti with Cheese: Used in the mountain cantons of Switzerland. Add thinly sliced rich cheese to the potatoes. Enhance with onions/or bacon as desired.
