In the bottom of your chilled highball glass, muddle 5-6 mint leaves and 5-6 raspberries by pressing lightly with your muddler. Add simple syrup, lime juice, and rum, then fill the glass with soda water and stir. Garnish with a sprig of mint (clap the leaves between your hands once to bruise them and bring out the aroma) and a wedge of lime.
