Cut avocado in half by slicing length-wise all around the pit. Twist the two halves apart; the pit will remain embedded in one half.
Carefully (but firmly) strike the heel of your knife into the pit; twist knife to dislodge pit. Use your thumb to push the pit off the knife blade.
Using the tip of the knife (careful!), make a crosshatch pattern in the flesh of each half. Cut all the way through the fruit but not through the skin.
Scoop out the diced flesh with a spoon. If not using immediately, toss with lemon or lime juice (or even water) to prevent browning.
Source: Bon Appetit
