sentence: add oil to pot sentence: add onion pieces into the pot sentence: add garlic pieces into the pot sentence: add parsley flakes into the pot sentence: add hot pepper flakes into the pot sentence: add mussels into the pot sentence: cover the pot and steam sentence: add wine stock and simmer into the pot sentence: cover the pot sentence: take mussels out from the pot and pour some parsley sentence: mix butter and flour sentence: boil mixture in the pan sentence: pour the soup on the mussels