Sopa Azteca (Tortilla Soup)

Instructions

1. Briefly toast the chiles by using tongs to carefully holding each chile an inch over a gas flame, turning for a few seconds until the chile is blistered and fragrant.  (Or alternately, if you have an electric stove, you can heat a skillet over medium-high heat and press the chiles down onto the hot skillet on each side for a few seconds until blistered and fragrant.)  Transfer the chiles to a blender or food processor and set aside.
2. Heat the olive oil in a large stockpot over medium-high heat.  Add the onion and sauté for 5 minutes until softened, stirring occasionally.  Add the garlic and sauté for 1-2 minutes more until fragrant, stirring frequently.  Using a slotted spoon, transfer the mixture to the blender along with the chiles.
3. Add the tomatoes to the blender, along with 1 cup or so of the stock (enough to help the mixture purée easily).  Then purée until completely smooth and no large chile flakes remain.
4. Transfer the blended broth mixture to the stockpot, add the remaining stock, oregano and epazote sprig (if using).  Cook over medium-high heat until the broth reaches a simmer.  Then reduce heat to medium-low to maintain the simmer and cook, uncovered, for 10 minutes.
5. While the soup simmers, go ahead and prep all of your add-ins.  (See notes below for instructions on how to fry tortilla and chile strips, if desired.)  Fill each serving bowl with a handful of tortilla strips and cooked chicken (if using), and set aside.
6. Give the broth a taste and season with however much salt and pepper you think it needs.
7. Ladle the hot broth into each serving bowl over the tortilla strips, top with a generous helping of avocado and cheese (if using).  Then load each bowl up with lots of your favorite toppings.  Serve immediately and enjoy!