Place mussels in a large bowl with cold salted water and soak for 20 minutes to expel sand and grit. Scrub shells with a stiff brush and pull beards firmly toward the hinge to remove. Discard any mussels with cracked shells or that remain open when tapped.
2 lbs fresh mussels
Heat olive oil in a large wide pot or Dutch oven over medium-high heat. Add finely chopped shallots and minced garlic. Cook for about 2 minutes until fragrant and softened but not browned.
4 cloves garlic, 2 shallots, 2 tbsp olive oil
Pour in the dry white wine and bring to a simmer. Add cleaned mussels, season with salt and black pepper, then stir once to coat.
2 lbs fresh mussels, 1 cup dry white wine, salt, black pepper
Cover the pot tightly with lid and cook for 5 to 7 minutes. Check at 5 minutes and remove all opened mussels to a serving bowl with tongs. Continue cooking the remaining unopened mussels for 1 to 2 more minutes. Discard any mussels that do not open.
2 lbs fresh mussels
Remove pot from heat and swirl in cold butter until melted and the sauce becomes glossy. Pour the sauce over the mussels, sprinkle with chopped fresh parsley, and squeeze lemon halves over the top. Serve immediately.
3 tbsp butter, ¼ cup fresh parsley, 1 lemon
