1In large bowl, mix chicken, celery and onions.
2In blender, place dressing, chopped parsley and the tarragon. Cover; blend on low speed 10 seconds. Blend on high speed 20 to 30 seconds or until smooth. Gently stir dressing into chicken mixture. Cover; refrigerate until serving time.
3Top each toast with 1 tablespoon chicken mixture. Garnish with parsley leaves.