Stir sugar into boiling water until dissolved. Place in the fridge (or speed it along in the freezer until chilled, but not frozen.
Margaritas:
Place coarse salt in a small bowl. Moisten the rim of your glass. Do this by running a lime wedge along the rim OR (my preference) put some simple syrup on the rim. You can dip it in the simple syrup or use your fingers to rub it on the rim of the glass. Dip the glass into the salt and twist it back and forth until the salt sticks. Set aside.
Place all remaining ingredients in a blender and process until smooth and slushy. Add more ice to thicken, if necessary. Serve immediately.
Notes
TIPS:
Make them strong: Since the alcohol, lime juice and simple syrup will be diluted by the crushed ice, make sure that your portions are on the stronger side.
Use chilled ingredients: If you use warm/room temp ingredients your ice will melt faster, and you'll likely need to add more ice to get a thick, slushy consistency. The more ice you add, the more you will dilute the flavor. So, plan ahead a bit and chill your alcohol, lime juice and simple syrup in advance.
Adjust to suit your taste preferences: I can't stress this one enough! When making your own cocktail you can control exactly how you want it to taste. Add more simple syrup for a sweeter cocktail, more lime juice for a more tart cocktail, and of course, increase or decrease the alcohol based on how strong you like your drinks. Use this recipe as a guide and go from there.
Adjust the recipe quantity: This recipe makes 4 margaritas, but you can easily double or even triple it to serve a crowd.
Serve immediately: Wait until you are ready to serve these Frozen Margaritas, then throw everything in the blender and mix them up and serve immediately. Simple syrup and lime juice can be prepped in advance and stored in the fridge.