Chill a highball glass with ice and set it aside.
Add strawberries and basil leaves to a cocktail shaker.
Muddle gently until the strawberries release juice and the basil smells fragrant, without shredding the leaves.
Add lemon juice and simple syrup to the shaker.
Fill with ice and shake firmly for about 10 seconds until well chilled.
Discard the ice from the glass and add fresh ice.
Double strain the mixture over the ice to keep it smooth.
Top slowly with club soda and listen for a light fizz.
Give one gentle stir to combine.
Garnish with a strawberry slice and a basil sprig.
