In a small saucepan, combine the sugar, orange juice, orange zest, lime juice, lime zest, and salt. Heat over medium-high heat, stirring frequently, just until the sugar is dissolved, about 5 minutes.
Remove from heat, let cool, and store in an airtight bottle in the fridge for 7-10 days.
To Make a Single Margarita:
Combine equal parts salt and granulated sugar in a saucer. Run a lime wedge around the rim of a margarita glass. Dip the margarita glass in the salt and sugar combo.
Fill a cocktail shaker with ice. Add in two ounces (¼ cup) of the margarita mix with two ounces (¼ cup) good quality tequila. Shake to chill. Pour into prepared glass.
To Make a Pitcher of Margaritas:
In a large pitcher, combine all of the margarita mix with 2 cups of tequila. Stir and chill until cold. Serve in glasses rimmed with salt.
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Notes
To make frozen, blended margaritas, freeze the mix in ice cube trays. Then, blend the cubes with equal parts tequila until smooth and frosty.This mix comes out tinted orange/yellow due to the orange juice. Many margarita mixes are dyed green unnaturally using artificial colors. If the color bugs you, a sprinkle of matcha powder whisked in will do the trick.