Chill a rocks or coupe glass in the freezer for a few minutes.
Spread the coarse salt on a small plate. Run the lime wedge around the outside of half the glass rim, then dip that edge into the salt to coat lightly. Set the glass aside.
Add tequila blanco, orange liqueur, and freshly squeezed lime juice to a cocktail shaker. Add the measured ice cubes. Shake hard until the shaker is very cold and frosty, 10–15 seconds.
Add fresh ice cubes to the prepared glass if serving on the rocks. Strain the margarita into the glass (fine-strain if you prefer fewer ice chips).
Garnish with the lime wheel and serve immediately.