Step 1

Combine the sugar and 1/3 cup water in a small saucepan. Cook over low heat, stirring, until the sugar dissolves, about 5 minutes. Let cool completely.

Step 2

Whisk together the tequila, lime juice, cooled sugar syrup, orange liqueur and 1 cup cold water in a medium bowl. Freeze until slushy in an ice cream maker according to the manufacturer's instructions, about 45 minutes (see Cook's Note). Transfer the frozen margaritas to a chilled pitcher. Store in the freezer until ready to serve.

Step 3

Fill a small plate with an even layer of salt. Moisten the rims of 4 chilled rocks or wine glasses and press into the salt to rim the edges. Divide the margaritas among the glasses. Serve with lime wedges.