Coarse salt (optional)
ounces tequila, divided
ounces orange-flavored liqueur, such as cointreau, divided
cups grapefruit juice, divided
grapefruit slices for garnish
Wet the rims of 4 glasses and coat with coarse salt (if desired); fill the glasses with ice. Pour 1 ounce tequila and 1/2 ounce liqueur into each. Top each with 3/4 cup grapefruit juice and stir. Garnish with a slice of grapefruit.