Add bourbon, fresh lemon juice, and simple syrup to a cocktail shaker.
If using egg white, dry shake all ingredients without ice for 10–15 seconds to emulsify.
Add ice and shake vigorously for a further 10–15 seconds until well chilled.
For straight up: double-strain into a chilled rocks glass.
For on the rocks: strain into an old fashioned glass filled with fresh ice.
Garnish with an orange slice and a maraschino cherry.
For the best result, use a reverse dry shake: shake with ice first, then strain out the ice and shake again without it - this produces a tighter, more stable foam from the egg white. Always use fresh-squeezed lemon juice; bottled juice will flatten the cocktail's bright citrus character.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Whiskey Sour.