Add all ingredients to a cocktail shaker with ice and shake until well chilled.
2.
Strain into a rocks glass over ice.
3.
Garnish with a lime wheel and (optional) kosher salt rim.
Notes
Quality tequila is key – ensure you're using 100% agave. And absolutely do not skip the fresh lime. Sour mixes are invariably inferior, and even bottled lime lacks the brightness of the freshly squeezed stuff.