For the simple syrup: Place the sugar and 1 cup water in a small saucepan over medium heat. Stir the mixture constantly and cook until mixture is fully dissolved, about 5 minutes. (This recipe will make more than you need for the mojitos but the extra can be stored in the refrigerator and used for other beverages or to cook with.)
For the mojitos: Add mint leaves, sliced limes and 1 cup simple syrup to a large (48-ounce) pitcher. Muddle these ingredients together with a muddler or the back of a wooden spoon.
Add the rum, club soda and lime juice. Add ice and stir. Divide mixture among 8 glasses and garnish with slices of frozen mango.
This recipe has been updated and may differ from what was originally published or broadcast.