Place the salt into a shallow dish larger than the diameter of the glass you are using. Rub each of 2 glasses with lime wedge. Dip the rim of each glass in the salt, and rotate gently to coat evenly. Set the glasses aside.
Fill a cocktail shaker halfway with ice. Add the tequila, orange liqueur, lime juice, blue curacao, and sugar. Shake hard for 30 seconds. Fill the prepared glasses with ice cubes. Strain the margarita mixture into the glasses. Garnish with star fruit or a lime wedge.
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