Cook the potatoes the day before
Cook the potatoes (uncovered) in boiling water over a medium heat for approx. 25 mins. until just soft. Drain the potatoes, leave to cool, cover and keep in the fridge.
Peel the potatoes the day before, grate coarsely using a rösti grater, season with salt, mix. Heat the clarified butter in a non-stick frying pan. Add the potatoes, fry for approx. 5 mins., turning occasionally. Shape the rösti into a cake. Continue to cook the rösti over a medium heat for approx. 15 mins. until a golden crust forms. Place a large, flat plate over the pan. Tip the rösti out onto the plate. Add a little clarified butter to the pan, slide the rösti back into the pan with the uncooked side facing down, cook for a further 15 mins.