1 Key lime (optional), quartered

Kosher salt (optional) for rims of glasses

3/4 cup Cointreau or other orange-flavored liqueur

1/2 cup reposado tequila

1/2 cup fresh Key lime juice

2 teaspoons superfine granulated sugar (optional)

Preparation Run a lime wedge (if using) around rim of each of 4 (6-to 8-ounces) glasses. Put salt (if using) on a small plate and dip glasses in salt to lightly coat rims. Blend liqueur, tequila, juice, and sugar (if using) in a blender until combined. Serve over ice (in coated glasses).