If you can’t find scallops in their shells, you can buy shelled sea scallops. Broil them in an ovenproof dish with the sauce drizzled over the top. Yield is 4 servings.
Remove tough muscle from sides if necessary. Marinate scallops in vermouth for 15 minutes.
Cut 1/2 cup of cold butter into tablespoon-sized pieces.
Remove from heat.
Simmer shallot in vinegar and wine on medium-high heat in a small, heavy saucepan until liquid is reduced to about 1 tbsp.
Reduce heat to low and cook, whisking in 7 tbsp. butter, 1/3 at a time, adding each new piece just before previous one has melted completely and occasionally lifting pan from heat to cool mixture. (Sauce should be the consistency of a thin hollandaise.) This process should take about 2 to 3 minutes.
Remove from heat and whisk in tarragon and salt and pepper to taste.
Keep warm off heat, covered.
Drain scallops and pat dry between paper towels.
Season scallops with salt and pepper.
Heat the remaining 1 tbsp. butter in a nonstick saucepan over medium heat.
Sear the scallops for 1 minute per side.
Put one scallop in each shell and spoon some sauce over top.
Mix the parsley, chives and breadcrumbs together in a small bowl. Sprinkle over the scallops.
Broil until golden and sauce is bubbly, about 1 to 2 minutes.