Preheat oven to 400° degrees. Heat oil in a large, oven- and flame-proof sauté pan on the stovetop until very hot, but not smoking.
Season fish on both sides with salt and pepper, and dust with Wondra flour. Blow off excess.
Put fish in the pan, skin side down, and press down on fish with a spatula. (The skin immediately contracts and buckles, but you want to keep it all in contact with the pan for maximum crisping.) Sear on the stovetop over medium heat until golden brown on the bottom, about 3 minutes.
Turn fish over, put the pan in the oven, and cook another 2 to 3 minutes, until a metal skewer can be easily inserted into the center of the fillet and, if left for 5 seconds, feels just warm when touched to your lip. Serve immediately.