01 - Fill a cocktail shaker with ice.
02 - Add the tequila or toasted barrel-aged gin, grapefruit juice, lemon juice, agave syrup, orange bitters, and Angostura bitters if using to the shaker.
03 - Shake vigorously for 15 seconds until the mixture is well chilled.
04 - Strain the cocktail into a chilled rocks glass filled with fresh ice.
05 - Add a grapefruit twist and optionally a dehydrated citrus wheel for garnish.