First,Preheat oven to 350°.second spread pecans on a rimmed baking sheet; bake until lightly browned,5 to 7 minutes.Set toasted pecans aside to cool.
In a medium bowl,whisk together sour cream,vinegar,and sugar until smooth.finally Add celery and apple; season with salt and pepper.Toss gently to combine.Crumble toasted pecans on top,and serve immediately.