Sauté the onion, celery, carrots, garlic, bay leaf, salt, pepper using a splash of vegetable broth. Cook for 4-5 minutes, until the vegetables are softened.
Add the vegetable stock to the pot and bring to a boil.
Add the pasta to the pot, and boil in the broth according to the time indicated on the package directions.
Add the chicken and parsley when there is about 2 minutes left for the pasta to cook.
Before serving, remove the bay leaf. Serve with a garnish of fresh parsley.
Notes
Instead of using seitan chicken, which is made from vital wheat gluten, feel free to add your favorite vegan chicken substitute. I recommend Abbot's Butcher chick'n. Or you could use chickpeas or cubed tempeh.