- 1 large shallot, finely chopped
- 1/4 onion, finely chopped (about 1/3 cup)
- 1/4 cup dry white wine
- 3 1/2 tablespoons unsalted butter, cut into 1/2″ cubes
- 1 tablespoon white wine vinegar
- 4 1/2 pounds mussels, scrubbed, debearded
- Freshly ground black pepper
- 2 tablespoons chopped flat-leaf parsley
- Special equipment: Cheesecloth
- Place shallot, onion, wine, butter, and vinegar in a large heavy pot. Add mussels, cover, and bring to a boil. Cook, gently shaking pot once or twice, until mussels open, 3-5 minutes (discard any mussels that don't open).
- Set a strainer lined with a double layer of cheesecloth over a bowl; set aside. Using a slotted spoon, transfer mussels to a large bowl. Pour mixture in pot through prepared strainer. Season broth with pepper and pour over mussels. Sprinkle with parsley.