1. Squeeze in juice from both lime halves into the simple syrup, and lightly muddle with mint. Add the rum and ice and stir to chill.
2. Pour everything into a glass, top with soda water and garnish with more fresh mint

Variations we've tried and loved:

COCONUT
Add 1.5 oz of fresh coconut water and cut back on a little bit of the soda water.  

For the advanced mixologists, you can try substituting a coconut fat washed Clever Fox Silver rum. Takes a bit more prep work for the infusion, but hits those coconut notes a bit more.