Photo: MarxFoods.com, Flickr
Rinse skin-on fish fillets and pat them completely dry. Using a sharp paring knife, score the skin, making three or four two-inch cuts through the skin but being careful not to tear skin or cut too far into the flesh. Season with salt and pepper and set aside.
Heat a nonstick pan over medium-high flame without oil. Once the pan is hot, add a couple of teaspoons of oil and swirl it around. Add a fillet to the pan, skin-side down, moving fillet as little as possible, until almost entirely cooked through but making sure skin is not burnt, 5 to 6 minutes. Using a fish spatula, gently flip fish and finish cooking for an additional 1 to 2 minutes.