Saute sausage in non-stick skillet, drain grease without leaving the skillet completely dry.
Grate a lot of potatoes (potatoes reduce by about half when cooked). Add them to the hot skillet. (The skillet should be heaping full if you want to serve 8.) Cook on medium to high heat, turning regularly as they brown. Keep turning the browned part in on itself for about a half hour.
Dice one or two onions and add to the potato mixture, Turning and flattening it into a skillet-sized cake. Cook about 15 more minutes.
Traditional Swiss rosti is served as a big flat brown cake on a round plate. To serve, invert a plate on top of potatoes in skillet, then turn the skillet upside down, leaving a nicely browned, round potato cake on the plate.