DIRECTIONS
Make the blackening mixture, if using. Combine the salt, garlic and onion powders, paprika, black pepper and cayenne pepper in a bowl and mix with your fingers. Alternatively, use your favorite commercial blackening rub.
Run your fingers over the fish fillets, feeling for bones. Pull out any you find with needle-nose pliers. Lightly oil the fish fillets with olive oil, then season generously with the blackening mixture.
Set up your grill for direct grilling and heat to high. Brush or scrape the grill grate clean and oil well.
Make the herb butter: Melt the butter in a small saucepan.
Arrange the fish fillets, flesh side down on the grill grate and grill until nicely browned, about 3 minutes. Using a spatula and tongs, carefully turn the fish over and continue to cook for 3 minutes until the fish is cooked through. To check for doneness, press the fish with the tip of your finger. It should flake easily.
Transfer the fish to a platter or plates, scale side down, and drizzle with some of the herb butter before serving.