Mussels with Herbed Bread Crumbs

1/2 cups coarse crumbs from a fresh loaf of crusty Italian or French bread

1/4 cup extra-virgin olive oil

1/4 cup finely grated Parmigiano -Reggiano (1/2 oz)

2 large garlic cloves, minced

2 tablespoons finely chopped fresh oregano or 3/4 teaspoon dried, crumbled

1/4 teaspoon dried hot red pepper flakes

1/4 teaspoon table salt

56 mussels (1 1/4 pound; preferably cultivated),cleaned and steamed , using half white wine and half water, then shucked, reserving

56 half shells

2 cups kosher salt

Accompaniment: lemon wedges