Wash the salmon fillet, dab dry and cut into cubes. Peel and chop the onion. Heat butter in a coated pan and fry the salmon cubes. Season with salt and take out. Sauté onion in frying fat until translucent. Deglaze with white wine and boil down for 3-4 minutes. Add fish stock and simmer covered for about 10 minutes
Wash the dill, shake dry and cut finely, except for a few flags for garnishing. Stir the crème fraîche into the simmering sauce. Add salmon cubes and dill and season the sauce with salt and pepper. Season to taste with lemon juice. Mix the sauce with hot, cooked pasta, garnish with the remaining dill