One pound frozen, pre-cooked mussels
1 Tbsp butter
2 Tbsp white vinegar
2 or 3 cloves garlic
1/4 cup water
1/4 of a large lemon
Pinch of salt (I used a locally-smoked sea salt. Very fun $3 splurge at our store's deli!)
Bring to a boil in a pot and let simmer for about six minutes to steam. I made four pounds of mussels, so at this point I gave it a good stir and let them steam a bit longer.
You can use any kind of vinegar, but I chose white vinegar for its clean flavor profile.
The cooking juice (pot likker?) is delicious- dip a crusty bread in, make it into soup the next day, thicken some with roux to make a sauce to pour over rice with your dinner....but don't waste it!