Step 1

Add the sugar and water to a medium-sized saucepan over medium heat. Simmer for 1-2 minutes, whisking occasionally, or until the sugar has dissolved. Remove from the heat and let cool to room temperature before using. You should end up with roughly 1 ¼ cups of simple syrup.

Step 2

Pour the lime juice into a 9x5-inch metal loaf pan along with the simple syrup and zest. Whisk until combined and freeze for 3-4 hours, or until mostly firm.

Step 3

Transfer the mixture to a high speed blender or food processor and blend for a minute or two, or until smooth. Avoid over blending to avoid heating it up too much.

Step 4

Pour the mixture back into the loaf pan and freeze for another 4 hours or up to overnight. Let sit at room temperature for a couple of minutes before serving with a sprig of mint, if desired.