Leave a tall glass in the freezer until it's nice and frosty.
Mix the water and sugar together in the chilled glass until sugar dissolves completely. Twist the scent and flavor from the mint leaves, then add them to glass. Fill the glass 1/4-full with bourbon, then add the ice. Garnish the glass with one last mint leaf.
Notes
Fun fact: The primary ingredient of a Mint Julep changes depending on where it's served. In Kentucky, it's bourbon. In Georgia, it's peach brandy. In Maryland, it's rye. Feel free to substitute any of these in as you please.