Combine some pink salt, sugar, and grapefruit zest on a small plate, using your fingers to work the zest into the salt and sugar. Use a grapefruit peel or some simple syrup to wet part of the rim of your glasses, then press them into the pink salt mix. Set aside.
pink salt, sugar, and grapefruit zest
Add frozen strawberries, grapefruit juice, water, and simple syrup to a blender and puree until smooth.
3 cups strawberries, 8 ounces grapefruit juice, 4 ounces water, 2 ounces simple syrup
Divide the strawberry mix between the rimmed drink glasses and top each with a splash of seltzer. Garnish with strawberry and grapefruit slices.
seltzer water, strawberry and grapefruit slices