Fill a cocktail shaker halfway with ice cubes.
Add the light rum, pineapple juice, and fresh lemon juice.
Shake vigorously for 10–12 seconds until well chilled.
Double-strain into a chilled cocktail glass.
Serve immediately, ungarnished.
The lemon juice here plays a supporting role - just enough acidity to lift the pineapple without dominating. For best results, use freshly squeezed lemon and a good-quality Cuban-style light rum such as Havana Club 3 Año.
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