Four 5- to 6-ounce frozen lobster tails, thawed (see Cook's Note)
1 stick (8 tablespoons) unsalted butter, at room temperature
1 tablespoon chopped fresh parsley
1 tablespoon minced shallot
1 teaspoon lemon zest
Kosher salt and freshly ground black pepper
To thaw lobster tails, refrigerate them for 24 hours until completely thawed. Alternatively, place them in a large pot and cover with cold water until completely thawed, 1 to 2 hours.