Allow this salad to sit a few minutes after tossing; the mozzarella milk and tomato juices emerge and add flavor to the dressing.
Cooks' notes:
•Salad, without vinaigrette, can be assembled 2 hours ahead and kept at room temperature. Salad can be dressed 1 hour ahead and kept at room temperature, covered.
•Vinaigrette keeps, covered and chilled, 1 week.