Preheat the oven to 350F. Spread the roughly chopped walnuts on a foil-lined baking sheet and roast in the oven for 10 mins
Make the dressing by whisking together the yogurt, mayonnaise, lemon juice, honey, and salt and pepper to taste
In a medium-sized bowl, add chopped apples, sliced red and green grapes, sliced celery, roasted walnuts, and craisins.
Add the dressing to the chopped fruit and toss carefully to coat everything well. Serve over a bed of butter lettuce leaves.