NYT Cooking: Blackening is a cooking technique that uses high heat and lots of seasoning to develop distinctive flavor by nearly charring the food in a cast-iron skillet. It’s particularly good for firm, lean white fish, such as catfish, snapper, trout or redfish. The fish is traditionally dipped in melted butter, then cooked in a dry skillet, but that can create billows of smoke. This smokeless method cook...