Shake all ingredients without ice. Shake vigorously for five seconds. Add ice and continue shaking until the shaker is chilled. Strain into a low glass with ice and finish with a twisted lemon peel.

* Vegan option: exchange egg white for canned chickpea (aquafaba) cooking water.
** To make sugar syrup just mix the same measure of sugar with water in a pan. Stir the sugar with water over high heat until you see the translucent liquid. Then leave on low heat without stirring for another five minutes