Add the simple syrup, yuzu juice, and fresh lime juice to the mint leaves. Gently muddle 6–8 times — just enough to bruise the leaves and release their oil and aroma without shredding them (over-muddling makes the drink bitter).

Add rum and ice

Pour 2 oz Bacardi Superior rum into the mixing glass. Add 4 ice cubes and gently stir for about 8–10 seconds to chill and lightly dilute the mixture.

Assemble in serving glass

Fill the chilled highball glass about three-quarters full with crushed ice. Strain the muddled rum-and-citrus mixture over the crushed ice, leaving the mint solids behind in the strainer if preferred (or include for extra aroma).

Top with soda

Carefully top the drink with 3 oz Fever‑Tree Club Soda. Use a bar spoon to give one or two gentle lifts from bottom to top to integrate soda without flattening the fizz.

Garnish and finish

Gently slap the reserved mint sprig between your palms to bruise it and wake the oils, then place it atop the drink. Add a lime wheel or wedge on the rim. If using, grate or twist the yuzu zest over the drink to release bright aromatics.

Serve

Insert a straw (optional) and serve immediately so the soda remains fizzy.