Spray a chilled rocks glass inside and outside with silver tequila
Pour 0.35 oz of agave syrup and 2 oz of silver tequila into a mixing glass
Add 2 dashes of Peychaud's bitters, 2 dashes of orange bitters and 2 dashes of grapefruit bitters
Fill the glass with ice cubes and stir gently
Strain into the rocks glass
Serve on a saucer with orange and grapefruit zests