Scrub the mussels very well, removing their beards and any dirt that clings to the shell. Put a little water or white wine just to cover the bottom of a broad pan or pot. Add the garlic and then the mussels. Cover and steam over medium-high heat for a few minutes until the mussels have opened. Remove the mussels from their shells and place in a bowl. Discard any mussels that have not opened.