In a hot kitchen, you can't just dump fresh lime, tequila, Cointreau, and simple syrup in a blender with ice: As you whir it, the room-temperature liquid melts the ice, so you get a cool, but not brain-freezing-frozen margarita.
The secret to real slushie-style margaritas at home (as opposed to the classic margarita on the rocks), without using corn syrup or artificial flavors, is to make your margarita base the day before and keep it in a sealed container in your freezer. The mix won't freeze, since there's so much alcohol and sugar in it, but it will drop way down in temperature: Ours clocked in at 5°F (-15°C) after an overnight rest. When the party starts, throw your ice in the blender, add your super-cold homemade margarita mix, get it whirring on "ice crush," and you're good to go. The result will be sweet-tart, boozy, and totally refreshing. You can find more recipes for fresh-fruit frozen margaritas here.
- 4 ounces (1/2 cup; 120ml) silver tequila (100% agave)
- 2 ounces high-quality triple sec or Cointreau (1/4 cup; 60ml)
- 2 1/2 ounces lime juice (5 tablespoons; 75ml), from 4 to 5 limes
- 4 ounces simple syrup (1/2 cup; 120ml); see note
- 12 ounces ice (about 3 cups)
At Least 8 Hours Before Serving: Combine tequila, triple sec, lime juice, and simple syrup in a sealable container that will fit in your freezer. Seal and place in freezer for at least 8 hours and up to 1 week (the mixture will remain completely liquid).
When you are ready to serve, add ice and tequila mixture to blender. Blend on highest setting, pulsing and scraping down sides as necessary, until completely smooth. Serve immediately.
For best results, chill the base for the margaritas at least eight hours before blending. The mixture can be made up to a week in advance and stored in the freezer. The base mixture can be doubled before it's placed in the freezer, but you'll need to work in two separate batches when puréeing. To make simple syrup, combine equal volumes of sugar and water in a small saucepan and heat until the sugar is dissolved.