Mix the potato, flour, eggs, scallions, salt, pepper, nutmeg and half the butter. Mix well together and shape into 12 small potato cakes. Heat the remaining butter in a non-stick pan and then cook the potato cakes until browned on each side. The cakes can be served immediately or kept overnight in the fridge. 15 minutes before serving reheat in a hot oven.
Mix the soured cream, dill and seasoning. Place a slice of smoked salmon on each potato cake and top with the cream mixture.