This salad is all about balance--sweet vs. tart and crunchy vs. chewy. Take it to a potluck or serve it at the holiday table.
Cook wild rice according to package directions. Let cool. Meanwhile, toast walnuts in a dry skillet over medium heat, stirring often, about 5 minutes.
In a medium bowl, whisk mayonnaise, yogurt, lemon zest, lemon juice, honey, salt and black pepper. Stir in rice, nuts, grapes, apple, celery and green onion. Garnish with additional celery leaves.