Trim the stalks from the fennel, cut the bulb in half lengthwise; then cut crosswise into very thin slices. Place in a large bowl with the capers and the dill. Make the dressing. Cut the quarter orange in small pieces and place in the work bowl of a food processor with the vinegar, mustard, sugar and salt. Process until smooth. With the motor running slowly, pour in the olive oil. Pour over the fennel, toss well and serve. SERVES:4