Step 1

Place sugar and 1 cup water in a small saucepan over medium heat. Cook, stirring, for 5 minutes or until sugar dissolves. Increase heat to high. Bring to the boil. Boil, without stirring, for 5 minutes. Remove from heat. Set aside to cool completely.

Step 2

Place watermelon in a blender. Blend until smooth.

Step 3

Place lime slices in a large jug. Using the end of a rolling pin, slightly crush lime to release juice. Add watermelon, soda water, lime juice and cooled sugar syrup. Stir to combine. Add mint.

Step 4

Combine extra sugar and lime rind on a small plate. Place 1⁄4 cup water in a separate bowl. Dip the rim of serving glasses into water, then in sugar mixture. Divide ice among glasses. Add watermelon mixture. Serve immediately.