DIRECTIONS To clean mussels:Scrub them with a brush under cold water and scrape off any barnacles with a knife. If the byssus, or beard , is still attached (most cultivated mussels have been trimmed mechanically), remove it by pulling it from tip to hinge or pulling and cutting it off with your knife. Do this just before cooking. Discard any with cracked or open shells.
To steam mussels: For 1 1/2 to 4 1/2 pounds mussels, put 1 cup liquid (water or a mix of water and white wine or beer) in a 4- to 6-quart pot. Bring to a boil, then dump in the mussels and cover. Reduce heat to moderate and cook, stirring occasionally, until the mussels open wide. This will take 3 to 6 minutes, but check frequently after 3 minutes. Scoop out the mussels with a slotted spoon (discard any that are unopened) and save the flavor-packed liquid if desired.