Sweet, crunchy, smooth, creamy, and slightly piquant, this salad is complex in flavor but very simple to make. We prefer Gorgonzola dolce latte for its creamy texture, but you could substitute a Roquefort or blue cheese. The watercress may be augmented with Belgian endive for a tart contrast to the peppery taste of the cress. If pears are not in season, substitute blanched carrot slices, and you may replace the celery with fennel.