Clean the salad, wash it and pluck it finely. Halve the avocado. Remove stone. Peel avocado halves, cut into slices and sprinkle with lemon juice. Cut salmon into wide strips.
Peel and finely chop the onion. Mix vinegar and horseradish. Whip the oil into it. Season to taste with salt, pepper and sugar. Fold in onion. Arrange salad, avocado and salmon on a plate.
Put some sauce on the salad. The rest of the sauce extra is enough. Baguette tastes good with it.