In a large bowl, soak the mussels in cold salted water for
30 minutes; rinse and scrape off the beards (the hairy tuft
protruding from one side of the shell).
In a large, deep skillet or saute pan, melt the margarine.
Saute the shallots and garlic until tender, about 5 minutes.
Add the wine, broth, and pepper; bring to a boil. Simmer,
uncovered, 5 minutes. Drain the mussels and add to the pan;
cover and cook until the mussels are fully open, about
8 minutes, shaking the pan frequently. Discard any mussels
that do not open.
Divide the mussels and broth among 4 deep soup bowls; sprinkle