Cut ends from all of the fruit, and then cut off the skin and bitter white pith with a paring knife. Cut the citrus segments out from the membrane and carefully put the segments in a shallow bowl, taking care to keep them whole. Squeeze the leftover peels and membranes over another bowl to get out any remaining juice.
Gently stir sugar and salt into juice, pour over fruit, and divide into soup plates. Cover and refrigerate until chilled, about 1 to 2 hours.