4 teaspoons grated lime zest
1/2 cup lime juice from 2 to 3 medium limes
4 teaspoons grated lemon zest
1/2 cup lemon juice from 2 to 3 medium lemons
1/4 cup superfine sugar
Pinch table salt
2 cups crushed ice
1 cup 100 percent agave tequila, preferably reposado
1 cup Triple Sec
1. Combine lime zest and juice, lemon zest and juice, sugar, and salt in large liquid measuring cup; cover with plastic wrap and refrigerate until flavors meld, 4 to 24 hours.
2. Divide 1 cup crushed ice between 4 or 6 margarita or double old-fashioned glasses. Strain juice mixture into 1-quart pitcher or cocktail shaker. Add tequila, Triple Sec, and remaining crushed ice; stir or shake until thoroughly combined and chilled, 20 to 60 seconds. Strain into ice-filled glasses; serve immediately.