Chill a cocktail glass with ice water and set aside.
Add the gin, fresh orange juice, absinthe, and grenadine into a cocktail shaker.
Fill the shaker with ice cubes.
Shake vigorously for 10–12 seconds until well chilled.
Discard the ice water from the cocktail glass.
Double-strain the cocktail into the chilled glass.
Serve immediately, ungarnished.
The absinthe in this recipe is a rinse-level quantity - just 15ml - but it transforms the drink entirely, adding aromatic depth without overwhelming the citrus. Harry MacElhone named the cocktail after the controversial 1920s surgical procedure by Serge Voronoff, which claimed to restore vitality by transplanting monkey glands into humans.
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