This is the closest we could come to the recipe for oysters rockefeller used by Antoine's in New Orleans, where the dish was created.
- Rock salt
- 12 bluepoint or other medium mild-flavored oysters, well chilled
- 4 tbsp. butter
- 4 tbsp. flour
- 6 scallions, trimmed and minced
- 2 ribs celery, trimmed, peeled, and minced
- Leaves from 1 bunch parsley, minced
- Leaves from 2 sprigs tarragon, minced
- 2-3 pinches cayenne
- Salt and freshly ground white pepper
- 3 tbsp. fresh bread crumbs
Fill 2 medium ovenproof baking dishes halfway with rock salt. Shuck oysters with an oyster knife over a medium bowl to catch oyster liquor (you should have about 1⁄2 cup), discarding flat top shells. Loosen oysters from bottom rounded shells with the knife. Nestle 6 of the shucked oysters, in their shells, into each bed of rock salt, cover with plastic wrap, and refrigerate.
Melt butter in a heavy medium saucepan over medium heat. Add flour and cook, stirring constantly with a wooden spoon, for 2 minutes. Add reserved oyster liquor and cook until pasty, about 2 minutes. Stir in scallions, celery, parsley, tarragon, and cayenne and salt and pepper to taste. Reduce heat to medium-low and cook, stirring occasionally, for 1 hour. Transfer to a food processor, add bread crumbs, and process to a smooth paste, 1–2 minutes.
Preheat broiler. Put paste into a pastry bag fitted with a 1⁄4" plain pastry tip. Uncover oysters and pipe paste completely over oysters. Broil until paste begins to brown and oysters are just cooked through, 5–7 minutes. Garnish each dish with parsley sprigs, if you like.