Finely chop enough fennel fronds to measure 1/4 cup; set aside. Cut fennel bulb in half lengthwise; remove and discard the tough outer layer, fennel core and any green stalks. Cut widthwise into thin slices and measure 3 cups; place in a large bowl. Add orange sections.
In a jar with a tight-fitting lid, combine the orange juice, oil, orange peel, salt and pepper; shake well. Pour over fennel and oranges; toss gently. Sprinkle with reserved fronds. Yield: 4 servings.