Choose a chilled coupe or rocks glass. Pour a few drops of lime juice onto a small plate and spread salt on another small plate. Moisten the rim of the glass with the lime, then dip the rim into the salt to coat lightly. Set glass aside.

Make watermelon juice (if not using premade)

If using fresh watermelon, cube about 2 cups of seedless watermelon and pulse in a blender until smooth. Strain through a fine mesh sieve into a container to remove pulp; press with a spoon to extract as much juice as possible. Measure 1.5 oz for the cocktail.

Shake

In a cocktail shaker, add 2 oz reposado tequila, 1.5 oz fresh watermelon juice, 0.75 oz fresh lime juice, 0.5 oz simple syrup, 0.5 oz triple sec, and 2 dashes Angostura bitters. Fill the shaker with ice (about 1 cup). Secure the lid and shake vigorously for 12–15 seconds, until the shaker is very cold to the touch and the drink is well aerated.

Strain and serve

Double-strain the mixture into the prepared chilled glass using a Hawthorne and fine mesh strainer to remove ice shards and any remaining pulp. If you prefer the cocktail over ice, fill a rocks glass with fresh ice and pour instead.

Garnish

Thread a thin watermelon wedge and a small lime wheel onto a cocktail pick or rest them on the rim. Optionally, express a small lime twist over the drink to release oils, then discard or float as preferred.