Notes: Rinse mussels well under cold water, scrubbing if needed. Pull out any beards by grabbing them and pulling towards the hinge-end of the mussels. (The beards look like little hairs poking out from between the shells.) Throw out any cracked mussels or open mussels that don't close when tapped with another mussel.
Time: 15 minutes
2 tablespoons unsalted butter
1 small onion, finely chopped
1 small fennel bulb, fronds removed, and finely chopped
4 medium cloves garlic, thinly sliced
1 tomato, small dice
1 teaspoon kosher salt (1/2 teaspoon table salt)
1/2 teaspoon freshly ground pepper
1 cup dry white wine, such as Sauvignon Blanc
2 pounds mussels (see note above)
3 tablespoons heavy cream (optional)
1 tablespoon juice and 1 teaspoon grated zest from 1 lemon
3 tablespoons minced fresh parsley leaves
1 baguette, sliced and lightly toasted
Melt 2 tablespoons butter in a large saucepan over medium-low heat. Add onion, fennel, and garlic. Season with salt and pepper and cook, stirring, until vegetables begin to soften (about 5 minutes). Add tomatoes and continue to cook until all vegetables are soft but not browned, about 5 minutes more.
Increase heat to high and add wine. Bring to a boil and let reduce by half, about 2 minutes. Add mussels, stir, cover, and cook, shaking pan constantly and peeking every 30 seconds to stir. As soon as all the mussels are open, transfer mussels to a bowl using tongs. Place pan lid over bowl to keep mussels warm.
Remove from heat and whisk in heavy cream. Return mussels to pot, add parsley, lemon juice, and lemon zest, stir to combine, then transfer to a warm serving bowl. Serve immediately with crusty bread.