How To make Rosti (Swiss Style Potato Cake)

1 3/4 lb Potatoes (see below)
3 oz Butter, lard or bacon fat
1 1/2 tb Water or milk
This is a favorite dish of German-speaking Switzerland. Besides being served as a side dish with meat or fish, it is sometimes eaten on its own, for lunch or even breakfast, with milky coffee. The potatoes should be boiled in their jackets the day before. These should be waxy potatoes of the potato-salad kind. The next day, peel them and grate them on the coarsest blade of the grater. Heat a large heavy frying pan, and let the fat get hot: then put in the potatoes, sprinkle with salt, and fry, turning them constantly. When they have soaked up the butter or whatever, add more. Now form a "cake" by pushing the potatoes from the edges of the pan into the middle and flattening down the top. Sprinkle with the water or milk, reduce heat, and cover with a lid or inverted dish. Shake the covered pan occasionally to keep the potatoes from burning, and leave on low heat for at least 15 minutes. The potatoes must stick together, but not to the bottom of the pan. When cooked, turn the cake out onto a plate, bottom side up, and serve. (Or alternately, brown the other side as well.) . Variations: (1) Saute 2 T chopped onions in the fat before adding the potatoes. Don't let them brown. Also note that in this version, the potatoes will need less fat. (2) Saute 2 - 3 1/2 oz. diced bacon before adding potatoes. You won't need any extra salt. (3) Sprinkle cooked potatoes with grated cheese before serving, and heat it briefly in the oven to melt it.