At the top of the page, it lists a blanket set of directions for all of the soups on this page:
First, combine all the ingredients except the noodles. Then stir, cover, remove from the heat, and allow to infuse for 2-3 minutes. Finally, strain the broth, add the cooked noodles, and serve.
The ingredients for the tortilla soup are chicken stock, canned tomatoes, onion, tortilla chips, jalapeño, cilantro, lime juice, and cumin seeds. It seems strange to me to use these ingredients (particularly the tortilla chips) solely as an infusion, then serving the soup as a plain noodles-and-broth affair. Has anyone had success with this?