Melt in a large heavy soup pot:
60 ml butter
Add and sautée for five minutes, stirring occasionally:
250 ml chopped onion
Add and sautée for another five minutes, stirring occasionally:
500 g sliced fresh mushrooms
Stir in and bring to a simmer (not a boil) for 15 minutes:
500 ml chicken stock
10 ml dill weed
15 ml paprika
15 ml soy sauce
Whisk together and add, simmering for another 15 minutes, still being careful to not boil:
250 ml milk
45 ml flour
Finally, blend together and stir in until completely combined:
120 ml sour cream
5 ml salt
3 ml ground black pepper (or to taste)
60 ml chopped fresh parsley
Serve immediately, with toasted croutons.