How to cook
Clean the mussels and put them to boil with the onion and black pepper until they open up. Cut the mushrooms into small pieces and cook them until soft with 1-2 tablespoons of butter. Remove the mussels from their shells and separately fry the flour with 2-3 tablespoons of butter.
Add the cream and a little of the broth from the mussels to get a nice sauce. Pour in the wine, a little black pepper and lemon, cut into slices. Once the sauce comes to a boil, put in the mussels with stewed mushrooms. Simmer the dish for 10-15 minutes, then serve.