Clean and wash the broccoli and cut it into small florets. Blanch in boiling salted water for about 5 minutes and drain. Peel and finely dice the onion. Separate eggs for the dough.
Mix egg yolk, salt and milk. Stir in flour. Beat the egg whites until stiff and fold in carefully. Sauté onion cubes and broccoli florets in portions in hot oil. Add 1/4 dough each and bake to 4 golden brown pancakes.
Arrange with salmon and some horseradish cream and serve garnished with dill and lemon.