2 parts fresh lime juice,              

2 parts simple syrup,                   

1 part white rum,                                     

1 part club soda, chilled   

Small splash of green colored creme de menthe (a little goes a long way), 

Fresh mint sprig

Stir together lime juice, simple syrup, rum, club soda and a small splash of creme de menthe. Serve over ice topped with a sprig of mint.