This method develops a flavorful crust (and is not as scary as it looks).
Set up grill for direct cooking and heat to medium-high. Clean and lightly oil hot grill. Season fish with salt and pepper, then brush both sides with oil. Cook, uncovered, 3 minutes. Flip and cook until just opaque in center, 3 minutes more. Top with flavored butter to serve.
Orange-Herb Butter Mash together 1 stick unsalted butter, 1/2 teaspoon grated orange zest, 2 teaspoons fresh orange juice, 1/4 teaspoon cayenne pepper, 1 clove garlic, minced, 2 tablespoons chopped cilantro, and 1/2 teaspoon coarse salt.