Rinse and scrub the potatoes well.
Place the potatoes in a pan. Cover with water. Add the salt. Bring to the boil. Lower the heat and simmer for 10 minutes (less if the potatoes are small). Tip: When pierced with a knife, the center of the potatoes should still be firm and offer resistance.
Drain the potatoes and cool to room temperature.
Peel the potatoes then grate coarsely. Divide into two portions.
Over medium heat, melt two tablespoons of butter in a frying pan. Spread half of the grated potatoes on the bottom of the pan. Cook until the underside is browned and crisp.
Using a wide spatula, flip the rösti to brown the opposite side.
Repeat the last two steps to cook the remaining half of grated potatoes.
Serve the rösti at once. You may top it with cheese, meat and vegetables.