Wash fresh limes thoroughly to remove any residues, then cut them into quarters.

In a blender, combine quartered limes, granulated sugar, and cold water. Blend on high for about 30 seconds.

Strain the mixture through a fine mesh sieve to separate juice from pulp and rinds.

Return the strained juice to the blender, add remaining cold water and sweetened condensed milk, and blend for an additional 20 seconds.

Fill glasses halfway with ice cubes, then pour the creamy mixture over the ice.

Garnish each glass with fresh mint leaves before serving.