Lobster Bisque - Alton Brown

Ingredients

• The shells of 2 lobsters, raw or cooked (about 1 pound)
• 5 sprigs thyme
• 5 sprigs tarragon
• 5 sprigs parsley
• 4 tablespoons room temperature unsalted butter, divided
• 1 large carrot, peeled and chopped
• 1 large white onion, peeled and chopped
• 1 stalk celery, chopped
• 1/2 teaspoon kosher salt
• 1/2 teaspoon white pepper, plus more to taste
• 2 tablespoons tomato paste
• 1/2 cup plus 2 teaspoons dry sherry, divided
• 6 cups seafood stock (preferably homemade but if not, see note)
• 2 tablespoons all-purpose flour
• 1/2 cup cooked white rice
• 1/2 cup heavy cream
• 1 teaspoon sherry vinegar
• Fresh chives, finely chopped