Cut the chives into rolls and grate the horseradish. Remove 2 egg yolks from the hard-boiled eggs for the sauce, dice the remaining eggs.
Mash the 2 egg yolks in a shallow bowl or a deep plate with a fork, mix with the crème fraîche, mustard and Condimento Bianco. Mix in the freshly grated horseradish and chives, season with salt and freshly ground pepper. Mix the diced eggs with this sauce.
The salad can be served straight away, but it tastes better if it can sit in the fridge for a while.