Mussel soup on fish broth

Rinse mussels, clean from algae. Crack shells and do not close when tapping to throw away. Throw out the "beard" "from each shell. Put the mussels in a saucepan, pour cider with pepper and roots. Cook under a lid over a high heat for 5-7 minutes. Shake the pan periodically until all the shells open. Do not open - throw it away. Remove the mussels from the shells, strain the decoction. Melt the oil in a pan, fry the onions until soft and transparent, add the flour, stir and dilute a little with fish broth. Add a decoction of mussels without sediment. Stirring bring to a boil, salt, put mussels. Sprinkle chopped parsley greens on the table before serving.