Peel the potatoes and the onion and grate them coarsely on a grater.
Press the moisture out of the potatoes and place them in a bowl along with the grated onion. Crack the egg into the bowl and season with salt and pepper.
Make 12 small flat rösti on a baking sheet with parchment paper (you can use a cylinder to shape them if necessary).
Press well so the rösti is firm.
Drizzle a little oil on each rösti.
Bake for 30 minutes in a convection oven at 200 degrees Celsius (392 degrees Fahrenheit) - cool down!
Garnish with generous amounts of lumpfish roe, 38% creme fraiche, and finely chopped red onion.