Wash, peel and roughly grate the potatoes. Place in a large fine sieve and squeeze gently so that the potato liquid comes out. Peel an onion and grate it finely under the potatoes. Add eggs, salt, pepper and a little nutmeg and mix everything together. If the dough is still too runny, add a little flour.
Heat the vegetable fat in the pan. Place small portions of dough in the hot fat, flatten a little and bake golden-brown, crispy potato pancakes.
Cut the second onion into very fine rings. Cover the potato pancakes with smoked salmon and onion rings and serve immediately.