First off - Make a batch of simple syrup--you can store in fridge for a few weeks.
Simple Syrup:
Put equal parts sugar and water into a saucepot and bring to a near boil, cool and store in fridge...dats it
The drink:
16 ounce tumbler
Muddle a 1/4" piece of fresh serrano chile along with 3-4 raspberries and 6-8 fresh mint leaves along with 1 TBSP of simple syrup in your glass.
Add juice of one lime
Add 2 oz white Rum
Add ice
Top off with club soda and stir.
Enjoy!

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If you are a candy-ass, leave out the serrano...
If you do not have a muddlin' stick, use a fork or whatever is available to smash the fresh ingredients to release oils/juices...