Squeeze the grapefruits in a bowl so as to collect all the juice, then pour it into a pitcher filtering it through a strainer.

Add the sugar and stir until melted, then pour in cold water, according to your taste. For a pleasantly refreshing cocktail use 1/3 of grapefruit juice and 2/3 of cold water.

Decorate the rim of the glasses with sugar and serve the pink lemonade with ice and a sprig of fresh mint.