In a shaker muddle strawberries with mint leaves and 2 cubes ice. Add rum, lime juice and simple syrup. Shake 30 seconds. Pour into a glass filled with ice. Top with club soda. Garnish with strawberry and mint sprig.
For Simple Syrup - boil 1 c water and 1 c sugar 3 minutes. Cool. Keep refrigerated up to 2 weeks.