Mangos have a very large, flat seed, so they cannot be sliced through the center. Upon examination, you'll notice the mango has opposing flat sides.
Place the mango with one flat side resting on the cutting board.
Slice the mango lengthwise along the flat side next to the seed.
Turn mango over and repeat on the other side. You should have two halves of mango pulp in the skin.
Set aside the seed with its remaining circle of pulp for later instructions.