11 If you are starting with somewhat old, dried out tortillas, great. If not and you are starting with relatively fresh tortillas, put them on a baking sheet and put them in the oven at 200°F for 10-15 minutes to dry them out a bit. It is best to start with tortillas that don't have a lot of moisture in them. Cut tortillas in half, and then cut the halves into 1/4-inch wide strips. Heat oil over medium-high heat in a 3-quart pot. Working in three batches, fry the tortilla strips in the oil, until lightly browned and crisp. Remove the tortilla strips from the pan and let drain on a paper-towel-lined plate.
2 Add the chopped onions to the pan, cook 2 minutes, stirring frequently. Add the chopped chile and cook for 2-3 minutes more, until the onions and chiles have softened. Add the garlic and cook for 30 seconds more. Add the broth, tomatoes, and salt. Increase the heat to high, heat until the soup begins to boil, then reduce the heat to a low simmer, cover and simmer for 15 minutes. Add the shredded chicken and cook until heated through.
3 To serve, pit, peel, and cut the avocado into 1-inch pieces. Divide half of tortilla strips among 4 individual serving bowls; ladle in soup. Top with avocado and cheese; garnish with remaining tortilla strips and cilantro. Serve with lime wedges.