Rim 2 cocktail glass with sea salt.
Pan fry grapefruit wedges in a little bit of sugar and water until caramalized.
Combine grapefruit juice, lime juice, and sugar in a glass. Stir until sugar is dissolved.
Stir in tequila, add ice and top up with club soda.
Garnish rim with grapefruit wedge and add a basil leaf to drink if desired.