In a large bowl, combine the celery, cranberries, apple, and chicken. Set aside. In a small bowl, whisk together the tahini, garlic, lemon juice, olive oil, water, and salt. The consistency should be pourable but not too thin and runny. Add the tahini dressing to the chicken mixture and toss to combine well. Divide the spinach between bowls and top with a scoop of the chicken salad.