1. With a sharp knife, cut away the skin and pith from the oranges and grapefruit. Cutting toward the core of the fruit and working over a bowl, cut away each segment, sliding the knife blade close to the membrane that separates them.

2. Place all the segments in a bowl. Squeeze any remaining juice from the membranes, then discard the membranes.

3. Peel the clementines and divide into segments. Add to the bowl, then add the lime juice. Sprinkle with the sugar, if using. Cover and refrigerate at least 2 hours, until chilled.

4. Using a slotted spoon, spoon the salad into dessert cups and garnish with the lime zest, if using. Serve chilled.

Variation

Sweet Citrus Salad

Make as above, but replace the 2 grapefruits with 1 pomelo or ugli fruit. These fruits have naturally sweeter flavors, so you can omit the sugar entirely.