Cardboard Plane

Select and pre-chill an Old Fashioned Glass.

Prepare a garnish of grapefruit zest twist for later use.

Shake the bourbon whiskey, Cointreau L'Unique triple sec liqueur, amaro, freshly squeezed lemon juice, pink grapefruit juice, and saline solution (or a pinch of salt) with ice.

Strain the mixture into the pre-chilled Old Fashioned Glass filled with fresh ice.

Express the grapefruit zest twist over the cocktail to release its oils, then use it as a garnish.