To coat fish or meat with pepper and/or other spices, then sear the meat in a hot skillet producing meat that is black on the outside but tender on the inside ... more on blacken here

It is a method of cooking in which meat or fish is seasoned with a spicy mixture then fried in a hot skillet until blackened on both sides.

make or become black; "The smoke blackened the ceiling"; "The ceiling blackened"

burn slightly and superficially so as to affect color; "The cook blackened the chicken breast"; "The fire charred the ceiling above the mantelpiece"; "the flames scorched the ceiling"

To defame; to sully, as reputation; to make infamous; as, vice blackens the character.

To make dark; to darken; to cloud.

To grow black or dark.

To make or render black.