Blackening fish (or other protein) isn’t juts applying a Cajun-spice blend and cooking it any old way you choose. Sure, you can sprinkle your fillets with a little seasoning and grill or bake them, but to really blacken something, you need extremely high heat and a disabled smoke alarm. Blackening fish in an almost-glowing cast-iron skillet creates a ton of smoke, but the end result is well worth the watering eyes and visit from the fire department. While the exterior make look burned, the taste is far from acrid. Here’s how to do it.