Wash potatoes and cut in half. Put into microwave-safe bowl with 2 tablespoons water. Cover and vent; microwave on high for 10 minutes. Let stand, covered, for 2 minutes. Uncover carefully to let steam escape; cool.
Cut potatoes into chunks. Combine potatoes with remaining ingredients; toss to coat with dressing. Cover; refrigerate at least 4 hours. Toss again before serving.
Recipe tested in 1000-watt microwave oven. Adjust cooking time for the wattage of your oven.