In a small bowl combine paprika, smoked paprika, onion powder, garlic powder, dried thyme, dried oregano, cayenne pepper, ground black pepper and kosher salt. Stir thoroughly to blend and set aside.

Prep fish

Pat the fish fillets dry with paper towels. Brush both sides of each fillet with olive oil (about 1/2 tbs per side). This helps the spice mix adhere and promotes crust formation.

Apply seasoning

Generously press the blackening spice mix onto both sides of each fillet so there is a uniform coating. Shake off any excess.

Heat the pan or grill

Heat a heavy cast-iron skillet or grill to medium-high/high heat until very hot (about 5 minutes). If using a skillet, add the melted butter and swirl to coat; it will foam briefly. If grilling, brush grates with oil and lightly oil the fillets instead of using butter in the grill.

Cook the fish

Place fillets in the hot skillet or on the hot grill. Cook without moving until a dark, charred crust forms and the edges look opaque, about 3–4 minutes depending on thickness. Flip carefully and cook the second side 2–4 minutes more until fish is opaque through and flakes easily with a fork (internal temp 130–140°F / 54–60°C depending on preferred doneness). Avoid overcooking.

Rest and serve

Transfer cooked fillets to a warm plate and let rest 2 minutes. Serve immediately topped with mango salsa and lemon wedges alongside.

Mango Salsa

Combine the diced mangoes, red bell pepper, red onion and minced jalapeño in a medium mixing bowl.

Add the chopped cilantro, lime zest and lime juice, then drizzle the extra-virgin olive oil and add honey or agave if using. Gently toss to combine.

Season with kosher salt and freshly ground black pepper. Taste and adjust — add an additional 1/2–1 tbs lime juice, a pinch of salt, or a little more honey to balance sweetness and acidity if needed.

Let the salsa sit at room temperature for 10–15 minutes to allow flavors to meld before serving. Keep chilled if holding longer than 30 minutes.