Add mezcal, pineapple juice, lime juice, simple syrup, egg white and 2 sages of Angostura bitters to a cocktail tin. Add 1 ice cube and shake vigorously for 30 seconds, to wipe the egg white.
Fill the cocktail tin with more ice and shake again for 20 - 30 seconds or until icy cold. Use a Hawthorne strainer to strain into a chilled coupe or martini glass. (Alternatively, you can serve this drink over a large cube in a rocks glass.)
To garnish, carefully dash a few droplets of Angostura bitter on the surface of the drink. Use a cocktail pick (or toothpick) to swirl the droplets into a pretty pattern. Cheers!