In a small bowl, whisk together the lemon juice, zest, yogurt, and honey. In a large salad bowl, gently toss the apples, grapes, celery, and walnuts with the dressing. Season to taste with salt and pepper. Substitute nonfat Greek yogurt for a lower-fat version if you like.
A scoop of Waldorf salad is delicious with a brunch omelet or frittata, or served on a bed of bibb lettuce or spinach alongside spanakopita or stuffed grape leaves.
190 calories, 10 g. fat, 4 mg. cholesterol, 36 mg. sodium, 23 g. carbohydrate, 4 g. fiber, 6 g. protein