Wash the asparagus, cut off the woody ends. Cut the stems in half lengthwise. Cook for about 10 minutes in 1/4 litre salted water. Meanwhile prepare the noodles in boiling salted water according to the instructions on the packet.
Peel and finely dice the shallots. Drain the asparagus. Heat the fat in a pot and fry the shallots in it until transparent. Dust with flour and sauté. Deglaze with asparagus water, wine and cream.
Bring to the boil and simmer for about 5 minutes. Season to taste with salt, pepper and horseradish. Wash salmon, dab dry and cut into large cubes. Sprinkle with lemon juice and simmer in the sauce for about 5 minutes.
Add the asparagus and heat in it. Serve with drained noodles. Garnish with lemon and chervil.