Boil up about 2 l salted water. Peel and chop the onion. Heat butter in a pot. Fry onion until transparent. Dust with flour and sauté briefly
Stir in milk and stock and bring to the boil. Simmer for about 5 minutes. Add gnocchi to boiling salted water and cook for 2-3 minutes until they float to the surface
In the meantime cut the salmon into fine strips. Clean, wash and shake dry the rocket. Then cut roughly. Season sauce with pepper, lemon juice and a little salt
Drain gnocchi well. Add salmon and rocket to the sauce and let it stand for a short time. Season to taste again