Pat the fish fillets thoroughly dry on both sides with scrunched-up paper towels. The surface should feel dry to the touch, which helps the seasoning and flour cling properly.
Season both sides well with salt and pepper. A full, even seasoning gives the fish flavor all the way through the crust.
Stir the flour and paprika together on a plate. The mixture should look evenly colored so the crust browns consistently.
Dredge each fillet on both sides in the flour mixture, pressing lightly so it sticks, then shake off the excess. The coating should look thin and even, not thick or dusty.
Heat a heavy based skillet over medium high heat until you see faint wisps of smoke, then add the oil and swirl to coat the base. The oil should look loose and hot almost immediately.
Lay the fish in the skillet and cook for 2 minutes on the first side, pressing gently if needed. You want a confident sizzle and a deep golden crust before turning.
Flip and cook the second side for 2 minutes more, then lift the fish out of the pan. The coating should be crisp and the fish should flake easily at the thickest part.
If the fish colors too fast, pull the skillet off the heat briefly, and if it sticks, leave it alone until the crust sets. Once the surface is properly browned, the fillet usually releases on its own.
Serve right away with lemon wedges and parsley or dill, if using. The crust is at its best while it is still hot and audibly crisp.