Chill a classic coup glass either in the fridge or fill with ice.

To a cocktail shaker, add the gin, Cointreau, lemon juice, and the egg white.

Seal the shaker and dry shake without ice for a minute or 2 until the mixture is very frothy.

Add several ice cubes or 1 large ice cube and shake again for several seconds until very cold.

Pour and double strain into the chilled glass. (Remember to remove the ice from the coupe if using ice to chill.)

Garnish with the orange peel if using.