Place kale in a large bowl. Add half of the apple, all of the celery, 1/4 cup pecans, and 1/4 cup raisins. Place the remaining apple in a blender or food processor along with the remaining 1/4 cup pecans, 2 tablespoons raisins, yogurt, Dijon, 3 tablespoons water, vinegar, salt and pepper. Puree until combined and slightly thick, adding an extra tablespoon or so of water if needed to thin. Pour over kale salad and toss to distribute. Garnish with sunflower seeds and blue cheese, if desired. I love a hefty sprinkle of both!