Whether you want to steam, roast, or grill mussels, I have you covered. See how easy it is to cook mussels below. Looking to learn more about mussels? See this guide to All About Mussels.
No matter how you choose to cook them, start with impeccably fresh and well cleaned mussels. Most mussels for sale in the U.S. are farmed and come to the market fairly clean, but a good rinse in cool water and a light scrubbing if they seem gritty – as well as pulling out any "beards" they have – just before cooking is a good practice.
Mussels are most commonly steamed. Some people simply pour a bottle of white wine and a few pounds of mussels into a pot and call it a day. You will end up with cooked mussels that way, to be sure, but they won't be nearly as delicious as they would be if you bothered to cook down a few aromatics before adding a bit less wine (or beer) and letting the alcohol cook off before adding the mussels. Now that is delicious. Try Mussels Steamed In White Wine or Mussels Steamed With Garlic and Chiles for more specifics.
In Belgium, where they are enormously popular, steamed mussels are traditionally served with french fries. A loaf of fresh, crusty bread is an equally fine accompaniment since pieces of it can be used to sop up the remarkably savory and delicious steaming liquid.
After simply steaming mussels they can be allowed to cool and topped with a dressing of some sort (a salsa of tomatoes and corn adds a spicy kick to the ones pictured here) to be served cold. A simple relish of shallots, vinegar, and fresh herbs like parsley and thyme is a classic option. They are remarkably tasty as long as the mussels are cooked, cooled, and served within the same day.