Blackened Mahi Recipe

Thaw/Pat Dry

If using frozen fillets, thaw completely in the refrigerator overnight. Rinse briefly under cold water and pat each fillet dry very well with paper towels. Dry surface helps spice stick and promotes a good sear.

Trim & Season Lightly

Trim any ragged edges or thin bits so fillets are even thickness for consistent cooking. Brush both sides lightly with lemon juice (about 1 tablespoon total) and then with the melted butter (reserve ~1 tbs of butter for finishing). Brush a little olive oil on each side if needed to help the rub adhere.

Make the Blackening Rub

In a small bowl combine paprika, cayenne, onion powder, garlic powder, dried thyme, dried oregano, black pepper, salt, and brown sugar (if using). Stir to blend evenly. Taste a tiny pinch to check heat level — adjust cayenne up or down to preference.

Apply Rub

Generously press the spice rub onto both sides of each fillet, coating edges. The layer should be thick enough to form a dark crust during cooking. Let sit at room temperature for 10–15 minutes while you preheat the skillet.

Preheat Skillet

Place a heavy cast-iron or stainless steel skillet over medium-high to high heat until it is very hot (about 3–5 minutes). You want the pan nearly smoking for proper blackening. Use a ventilation fan or open a window; the spices will toast and produce aroma.

Add Fat to Pan

Add 1 tablespoon of olive oil (or clarified butter) to the hot skillet and swirl to coat. The oil should shimmer but not burn.

Sear Fillets

Working in batches if necessary to avoid crowding, place fillets spice-side down in the skillet. Press gently to ensure full contact. Cook without moving for 2.5–3 minutes, until the spice crust is dark brown/black and the edges are opaque.

Flip & Finish

Carefully flip each fillet using a spatula. Add the reserved melted butter over the top of each fillet (or spoon it into the pan) to baste while the second side cooks. Cook 2–3 minutes more, until the fish flakes easily with a fork and reaches an internal temperature of 135–140°F (57–60°C) for moist, just-done mahi. Thicker fillets may need an additional 1–2 minutes.

Rest

Transfer fillets to a warm plate and let rest 2–3 minutes. Resting lets juices redistribute and retains moisture.

Garnish each fillet with a sprinkle of chopped parsley and a lemon wedge. Serve immediately with hot sauce or remoulade on the side. Blackened mahi pairs well with rice, sautéed greens, or a simple slaw.