Slice your mango on either side of the pit located in the middle of the fruit. It's typically about half an inch thick. Then, you'll be left with 2 rounded slices of mango (the sides) and a rectangular shaped pit (the middle piece). Using your knife, slice the insides of your mango slices vertically and horizontally, creating a grid of mango cubes. This is similar to how you'd also slice the inside of an avocado. Then, scoop out your mango cubes. You can also slice off the remaining mango surrounding the pit. Be careful with your knife!