In a cocktail shaker, combine arugula, mint, cucumber slices, lemon slices and lime slice. Muddle until the arugula, mint and cucumber are all smashed and the citrus juices are released.
Add the Pimm’s No. 1 and simple syrup. Fill with ice, cover and shake vigorously until chilled, about 15 seconds.
Fill a highball or Collins glass with ice. Strain the cocktail into the glass, then top up with ginger ale and stir gently to mix. Garnish as desired.
