Mix crème fraîche with horseradish and set aside to cool. Mix salt, vinegar, pepper and the two oils to make a salad dressing. Peel the shallots and cut into very fine rings, add to the salad dressing.
Rinse the watercress and shake it out properly, pluck the small twigs from the stems. Chop garden cress from the beds. Turn both types of cress briefly in the salad dressing to the other side, then arrange on six plates. Add two slices of salmon to each. Pour the horseradish sauce .on the salmon. Place the caviar on top. Cut the chives into rolls and sprinkle them around. Put on the table with toast. Serve with dry white wine, e.g. a Riesling Spätlese or a Sancerre.
Tip: As an alternative to the fresh chives, you can also use the freeze-dried ones.