If salting the rim, rub a lime wedge around the rim of the glass and dip in salt.
Fill the glass with ice.
Add tequila, grapefruit liqueur and lime juice. Stir briefly.
Add lime wheel and top with grapefruit soda.
Add grapefruit wedge for garnish.
Video
Notes
Using the grapefruit liqueur is totally optional, I just happened to have some. I used Giffard's Créme de Pamplemousse.Rimming the glass with salt is optional - I like to use Himalayan Pink Salt.