Slice in half lengthwise around the pit, then twist the two halves in opposite directions to separate.
Hold the half with the pit in a kitchen towel. Carefully knock the bottom end of a knife blade into the pit.
Twist the knife to remove the pit. Use the edge of a cutting board or trash can to pull the pit off the knife.
Slice or dice the avocado in its skin with a paring knife and scoop out the flesh with a spoon.