1 to 1 1/2 cups fresh squeezed grapefruit juice (from about 2 large grapefruit)
3/4 cup tequila
1/2 cup Triple Sec
1/2 cup fresh-squeezed lime juice
2 Tbs superfine sugar (plus extra for rim)
4 cups crushed ice
Run a lime wedge over the rim of each glass and dip in superfine sugar. Shake all ingredients together in martini shaker, strain out the ice, carefully divide the margarita mixture among four glasses and serve.