Heat a large ovenproof skillet (preferably cast-iron) over medium-high heat. When the skillet is piping hot, add the remaining 1 tablespoon oil and swirl to coat the bottom of the pan. Place the fillets in the skillet, skinned side up, and cook until deep reddish-brown on their undersides, 60 to 90 seconds.☞ TESTER TIP: The spices and oil will smoke! That’s part of the “blackening” process— crack open a window or turn on the vent fan, don’t panic, and don’t inhale too deeply.