Rub the rim of your glass with a wedge of blood orange. Dip the rim into a plate of salt. Set aside.
Add the tequila, blood orange juice, lime juice, and sugar to a cocktail shaker with ice. Shake well until the sugar is dissolved.
Fill your prepared glass with ice and pour the mixture in. Top with club soda and give it a gentle stir. Garnish with a slice of blood orange and serve.