6(8- to 10-ounce)fish filletspreferably redfish substitute with bass cut about 1/2 inch thick
Heat a large cast-iron skillet over very high heat until it is beyond the smoking stage and you see white ash in the skillet bottom (the skillet cannot be too hot for this dish), at least 10 minutes.
Meanwhile, pour 2 tablespoons melted butter in each of 6 small ramekins; set aside and keep warm. Reserve* the remaining butter in its skillet. Heat the serving plates in a 250-degree oven.
Thoroughly combine seasoning mix ingredients in a small bowl, Dip each fillet in the reserved melted butter so that both sides are well coated; then sprinkle seasoning mix generously and evenly on both sides of the fillets, patting it in by hand. Place fish in the hot skillet and pour 1 teaspoon melted butter on top of each fillet (be careful, as the butter may flame up)