Prepare the chicken. If using my seitan chicken, bake in the oven as directed. If using a store-bought chicken, pan cook according to the package directions.
In a large/deep skillet (or pot if you don't have a skillet), heat the onion over medium heat. Cook five minutes, until translucent.
Add the Cajun seasoning and toss.
Add the broth, tomatoes, and pasta. Bring to boil and cook until pasta is al dente, according to the package directions.