Cut kale leaves away from stems. Stack leaves, roll them up, and cut into thin ribbons; you should have about 6–8 cups. Combine kale and salt in large bowl and massage salt into kale for about 2 minutes (my youngest daughter likes to do this part!). Stir cranberries, onion, apple, and walnuts into the kale. Add oil and vinegar and toss. Sprinkle with bleu cheese.