Heat the oil in a 4-quart saucepot over medium-high heat. Add the onions, garlic and cumin and cook for 5 minutes or until the onion is tender.
Stir the broth, tomatoes and chipotle pepper in the saucepot and heat to a boil. Reduce the heat to low.
Tear 5 of the tortillas into pieces. Add the tortillas to the saucepot and cook for 25 minutes.
While the soup is cooking, prepare the fried tortilla strips: Cut the remaining tortillas in half, then crosswise into 1/4-inch strips. Heat the oil in an 8-inch skillet over medium heat until hot. Add the tortillas and cook for 1 to 2 minutes or until they're golden. Remove with a slotted spoon and drain on paper towels. Season as desired.
Pour half of the broth mixture into a blender or food processor. Cover and blend until smooth. Repeat with the remaining broth mixture. Return to the pot and stir in the cilantro. Season to taste.
Divide the soup among 8 serving bowls. Top each bowl of soup with tortilla strips, avocado, green onion and a splash of lime juice.
Tip: *Chipotle chili peppers in adobo sauce are sold in cans and may be found in the Mexican or ethnic food section of grocery stores.