Add ingredients except soda water to a cocktail shaker with some crushed ice. Shake until ice is fully melted.

Strain into a highball ice with cracked ice. Top with soda water. Garnish with a lime wheel and serve with a straw.

Combine ingredients in a small saucepan over medium heat. Simmer, stirring often, until sugar is dissolved. Remove from heat and let cool to room temperature.

Pour syrup into jug of a blender and blitz. Strain through a fine mesh sieve into an airtight jar, refrigerate for up to 1 month.