Generously coat the flesh side with the seasoning mixture (you will likely have leftover seasoning if only cooking 2 filets.)
Heat 2 tablespoons of oil in a large non-stick skillet over medium-high heat. When oil is shimmering swirl the pan so that the oil evenly coats the bottom of the skillet.
When very hot, place fish filets flesh side down, cook, without touching, until a dark brown (or blackened) crust has formed and the fish is almost cooked through, about 6 minutes.
Flip the fish onto the skin side press down with the back of a spatula to flatten the filet and the skin is flush with the skillet (it tries to curl). Continue to cook until the fish is cooked through, or completely opaque and flakes easily, about 3 more minutes.
Carefully, using a sturdy spatula, transfer the cooked fish to plates and serve with a wedge of lemon and garnish with fresh parsley (if desired).