Cucumber, Celery and Apple Salad with Yogurt and Walnuts

This crisp-creamy salad is reminiscent of a classic Waldorf salad, but tangy yogurt replaces the mayonnaise, for a lighter, fresher flavor. Thin half-rounds of cool cucumber and chopped dill fit seamlessly into the mix of apples and celery. For a light main dish or an elegant first course, lay slices of smoked salmon on each serving before sprinkling with the dill and walnuts.