Lime wedges or triangular slices of fresh grapefruit
Make the Rim: Pulse sugar, salt and lime zest in a small food processor or spice grinder until fully blended. Spread mixture out on a small plate, making sure it’s spread wider than the diameter of your glass.
Make the Margaritas: Combine everything in a blender: grapefruit juice, tequila, cointreau, lime juice and ice. Puree until smooth. Pour into a pitcher and serve or pour into a plastic container and freeze until ready to serve. These are great to make ahead. They get nice and slushy if you leave them in the freezer overnight. Just stir, scoop and serve.
To Serve: Make a little cut in a lime wedge, push it down over the rim of a glass, and run it around the perimeter to wet the edge. Press the moistened edge into the rimming mixture. Give the margaritas a good stir before serving. Pour or scoop into rimmed glasses. Garnish with lime wedges or grapefruit slices.