Combine the tequila, Blue Curacao and lime juice with ice in a cocktail shaker, or in a covered mason jar. Then shake, shake, shake everything together.
Salt the rims:
Pour sugar syrup or agave nectar into a shallow bowl.
Spread the salt in a separate shallow bowl - make sure both dishes are wide enough for the rim of your margarita glass to fit into.
Dip the rims of two margarita glasses first in the sugar syrup or agave, then in the salt, turning to coat the entire rim.
Assemble the drinks:
Carefully add 2-3 ice cubes to each glass without disturbing the salted rims.
Strain the margarita mixture carefully over the ice. Serve the drinks immediately.
Notes
If you're like me and don't own any margarita glasses, use regular cocktail glasses or my go-to—pint-sized mason jars. They're perfect for a small drink.
Stashing your glasses in the freezer ahead of time to get them really cold for your drinks.