- 2 lb mussels (35 to 45; preferably cultivated), scrubbed well and beards removed
- 1/3 cup dry white wine
- 2 hard-boiled large eggs
- 2 tablespoons white-wine vinegar
- 1/4 teaspoon salt
- 1/4 teaspoon black pepper
- 1/4 cup extra-virgin olive oil
- 1/2 cup finely chopped celery
- 1/2 cup pickled cocktail onions, trimmed and finely chopped
- 2 tablespoons chopped fresh tarragon
- Garnish: seaweed
- Cook mussels in wine in a 4- to 6-quart pot over moderately high heat, covered, until mussels just open wide, checking frequently after 4 minutes and transferring opened mussels to a large bowl using a slotted spoon. (Discard any unopened mussels after 8 minutes.)
- Pour cooking liquid through a fine-mesh sieve into a 1- to 2-quart heavy saucepan and boil until reduced to about 3 tablespoons, about 5 minutes. Transfer to a bowl.
- Finely chop eggs, then add to reduced liquid along with vinegar, salt, and pepper. Add oil in a slow stream, whisking, then whisk in celery, onions, and tarragon. Season vinaigrette with salt and pepper.
- Remove mussels from shells and reserve 1 half shell from each mussel. Stir mussels (but not shells) into vinaigrette and marinate, covered and chilled, at least 1 hour. Rinse and dry reserved mussel shells, then chill in a sealed plastic bag until ready to use.
- Arrange shells on a large platter lined with seaweed and spoon a mussel with some vinaigrette into each.
- Available at seafood shops by special request.