Combine sugar and water in a small saucepan over medium-high heat to create a simple syrup. Simmer, stirring occasionally, for about 30 minutes or until all the sugar has dissolved and the simple syrup has reduced by about half.
Add mango and lime juice to a food processor and puree until smooth.
Mix together simple syrup and mango puree until combined. Transfer to an 8x8" glass baking dish, cover, and freeze for about 10-12 hours.
Notes
You can use bottled lime juice or even lemon juice instead, if desired, one lime yields about 2 tablespoons of juice.
You can also use frozen mango instead of fresh, if desired, use about 3 cups and allow to thaw before use.