Boil the potatoes in salted water, preferably the day before. Allow to cool.
Preheat oven to 180 ° C. Peel and grate potatoes. Stir in whipped cream and sour cream, season with salt and pepper.
Heat oil in a pan, spread and fry potato mixture in it. Bake in the oven on the bottom rack for about 40 minutes.
Unmold potato cake, portioning and garnish with salmon, cream, caviar and salad.