Preheat the oven to 350?F. Line a baking sheet with parchment paper.
With a sharp knife, make 5 slits, at an angle and about 1 1/2 inches apart, on each side of the fish. Rub 1 tablespoon of the olive oil over each side of the fish, then season each side with 1 teaspoon of the Creole seasoning.
Place the fish on the prepared baking sheet. Combine the kosher salt, herbs, lemon zest and juice, orange zest and juice, and black pepper in a large mixing bowl. Mix well. Mound the mixture evenly on the surface of the fish, leaving the head and tail uncovered. With your fingers, firmly press the mixture into the flesh.
Bake for 1 1/2 hours. Remove from the oven and let cool for 2 minutes. With the back of a heavy spoon or a mallet, lightly pound the salt crust to crack it open, beginning at the tail end. Carefully pull off the salt crust. Then, with a small spatula or wide knife, remove the flesh from the bone from the top side of the fish. Remove the backbone, then serve the flesh from the bottom side of the fish. Spoon some salsa over each serving.
Yield: about 8 servings