Clean and wash broccoli and cut into florets. Peel and chop stems. Bring 500 ml of water to the boil, stir in the broth. Add the broccoli and cook covered for about 5 minutes. Lift out broccoli and save the broth.
Dice the onion and sauté in butter. Flour over it and sweat. Deglaze with the stock and cream, stirring well. Bring the sauce to the boil and simmer for 5 minutes. Cut the smoked salmon into strips and add. Fold in broccoli and season with salt, pepper and lemon juice.