Rub the rim of a Collins glass or mason jar with a lime wedge, and dip it in a small plate of salt. Add tequila, grapefruit juice, lime juice and ice to a shaker. Shake and strain into an ice filled glass.
Top with the grapefruit soda, a pinch of salt, and gently stir Don Javier style with the knife used to cut the lime.
Garnish with a grapefruit and lime slices. Taste and adjust. If you prefer a sweeter Paloma, add a pinch of salt right to the glass. Add more lime juice for more of a citrus zing.