Place the mango upright with the stem end down on the cutting board.
Slice down the length of the mango, just to the outside of the center of the fruit so that your knife slices parallel to the long flat seed, but doesn't bump into it.
Repeat on the other side of the pit so that you have two side "cheeks" and one flat pit piece.
Cup one mango half, skin side down, in your palm. Carefully slice vertical cuts into the flesh, up to the skin, but not going through the skin. If you would like mango slices instead of mango pieces, skip ahead here to Step 5.
Slice crosswise to make a grid or crosshatch pattern, again being careful not to slice through the skin.
Press the skin from the back to invert the mango half, "popping" the fruit from the skin.
Slice the fruit from the skin or scoop the flesh off of the skin with a large spoon.
Trim any additional flesh from the sides of the mango pit piece. Cut away the skin on that flesh and slice into pieces.