Fennel's sweet anise flavor complements most fruits. This lovely combination is equally good before or after the main course.
Arrange arugula to make a bed on each of four salad plates.
Cut orange crosswise into thin slices. Arrange one-fourth of slices over arugula on each plate.
Cut away feathery tops of fennel at base of round stalks and discard. Slice off bottom of bulb, remove tough outer layer of bulb and discard both. Halve bulb vertically. Using very sharp knife, cut each half crosswise into very thin slices. Arrange over orange slices.
Separate onion slices into rings and arrange over fennel. Add olives. Sprinkle with salt and pepper.
In small bowl, whisk oil with orange juice or concentrate and zest. Drizzle dressing over each salad. Serve immediately.