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