Heat olive oil in a large stockpot or saucepan over medium heat. Add corn and onion; cook until lightly caramelized. Add chicken broth and chipotle chile; let simmer 20 minutes over low heat. Add the tomatoes, avocado, lime juice, 1/4 cup cilantro. Season with salt and pepper. Remove and discard the chipotle chile.
Place one-sixth of the tortilla strips in the center of six soup bowls; ladle soup around the crisps. Garnish with remaining cilantro and sour cream. Serve with a wedge of lime.
This is the exact recipe -- I prefer to put avacado in just before serving -- so it is not warmed.