For the juice:
For the syrup:
- Add the watermelon to a blender and blend until smooth. Pour through sieve to remove pulp.
- Make the syrup by adding the sugar, mint, and water to a saucepan and heating at medium high heat. Stir constantly. When it starts to simmer, reduce the heat to low and cook for another 2 minutes. Allow to cool and remove the mint leaves.
- Combine the bourbon, watermelon juice, and 2 Tablespoons mint syrup and shake.
- Add some roughly crushed ice to your glasses, pour the cocktail over it, and top with club soda.