If you do not have cooked rice on hand, cook rice in advance, fluff with fork and allow to cool.
Place onion in a food processor fitted with the S blade and pulse until onion is finely chopped.
Scrape onion into a bowl and repeat the process with the celery and baby kale, separately.
Add walnuts and cranberries to chopped vegetables and stir until well combined.
Scape cooled rice into chopped vegetables with a fork (to help separate the grains) and stir until well combine. You may find it helpful to scrape and stir ⅓ of the rice at a time.
Add vinaigrette and diced apples to the salad, stir and serve or refrigerate for 1-2 days for later use.