If using salt, rub a grapefruit wedge around the glass rim and dip lightly into flaky sea salt or smoked salt. Set the glass aside to dry while you prepare the cocktail.

Dry shake (if using egg white)

Add the Casa Dragones Reposado (2 oz), fresh lime juice (0.75 oz), agave nectar (0.5 oz), Cointreau (0.5 oz), fresh grapefruit juice (0.5 oz), egg white (0.5 oz, optional), and 2 dashes of Angostura bitters to a cocktail shaker. Seal and shake vigorously without ice for 10–15 seconds to emulsify the egg white and build a silky foam.

Wet shake

Open the shaker, add the ice cubes (about 6 cubes), reseal and shake hard for 12–15 seconds until the outside of the shaker is frosty and well chilled.

Double strain and serve

Using the Hawthorne strainer and then a fine mesh strainer, pour the cocktail into the prepared rocks glass over fresh large ice (or into a chilled coupe if serving neat). Double straining removes small ice shards and any egg white solids for a smooth texture.

Finish and garnish

Express a grapefruit twist over the drink by holding it peel side down and giving it a quick twist to release oils, then rub the peel around the glass rim and drop it into the drink. If desired, add a final tiny drop or two of Angostura bitters onto the foam and gently drag a toothpick to create a small design. Serve immediately.