In a blender, add the cubed mango, sugar, mint, and lime juice. Blend until the mixture forms a nice, smooth puree.
Add in the rum and mix well.
Evenly divide the mixture in glasses filled with ice.
Stir in sparkling water.
Garnish with more mint.
Notes
You can use any white rum that you really enjoy. If you want, you can also add the rum into the blender. I do not recommend adding in the sparkling water to the blender.