Allow the fish or chicken to come to room temperature. Pat the fish dry with a paper towel (the drier the skin, the less it will stick and the crispier it will be). Heat a glug of neutral (high heat) oil in a large frying pan over high heat until smoking hot. Season the fish or chicken liberally with salt. Place the skin-side down and press it into the pan, ensuring good contact between the skin and the pan as the proteins constrict. Allow the meat to sear until it moves easily when gently nudged with a spatula (meaning the skin is fully crisped and released from the pan).