Blend the blueberries in a blender or food processor until smooth. Strain through a mesh sieve to remove the pulp.
Combine the blueberry juice, lime juice, tequila, orange liqueur, and simple syrup together in a cocktail shaker and set aside.
Run a lime wedge along the rim of two glasses then dip the rims into a shallow bowl or plate with salt or sugar.
Fill the glasses about ¾ full of ice and pour in the drink mixture, garnish with lime wedge and serve.
Notes
Want a frozen margarita? Add all of the ingredients except the salt and sugar to a blender and pulse until a slush forms. Pour into salt or sugar rimmed cups and enjoy.