Cook 2/3 of the potatoes a day in advance and leave to cool overnight in the fridge. Peel and grate the cooked potatoes. Mix the potatoes with the remaining ingredients and season to taste. Preheat the pan to medium heat and add a little clarified butter. Shape the potatoes into 8 balls and place them in the pan (not too close together). Using an iron spatula, press the balls into a disc about 1 cm in size and fry slowly until golden brown and crispy. Then turn over and fry the other side too.
SERVING: Serve the potato pancakes with apple sauce or a chive and sour cream sauce.