Adapted from liquor.com
oz Tequila (preferably reposado)
.5 oz Fresh lime juice
Pinch of salt (or to taste)
Grapefruit soda (Jarritos or Squirt work best)
Garnish: Lime Wheel
Combine the tequila, lime juice, and salt in a tall glass. Add ice and top off with grapefruit soda. Stir gently and garnish a lime wheel.