Pre-heat oven to 350°F. Spread chopped pecans on baking sheet in a thin layer and bake 4-6 minutes or until golden brown.
For the salad: Thinly slice celery, reserving some celery leaves. Core and thinly slice apples, halve grapes and chop turkey. Add all salad ingredients (through feta) to a large bowl. Cover and refrigerate until ready to serve.
For the dressing: In a small bowl, whisk together white wine vinegar, oil, salt and pepper. Add to salad before serving and toss to combine. Garnish with reserved celery leaves.