There are a couple of ways to blister your chiles. 1. Preheat the broiler. Cover a baking sheet with aluminum foil and dust with nonstick cooking spray. Broil the chiles until blackened, about 10 minutes. Transfer to a bowl, cover and let cool (about 15 minutes). Once cooled, the skin will easily peel off. Slice the chile down the middle to remove the seeds and chop into bite size pieces. 2. If you have a gas stove you can blister all sides of the chiles right over the flame until done and following the same bowl method above to remove the skin.
Preheat oven to 400 degrees F. Halve tortillas then cut crosswise into 1/2-inch-thick strips. On a baking sheet, toss the tortilla strips with 1 Tablespoon oil and cumin. Bake until golden, about 10 minutes. Season immediately with salt.
In a large deep skillet or Dutch oven, heat the remaining 2 Tablespoons of oil on medium-high heat. Add corn and cook until browned at the edges, 10 to 12 minutes. Add red onion and garlic, season with salt and pepper and cook until onion is softened, about 5 minutes. Stir in vegetable broth, fire-roasted tomatoes and diced chiles. Bring to a boil and turn off. Season to your liking with salt and pepper.
Divide tortilla strips among soup bowls and ladle soup on top. Top each bowl with chopped avocado, squeezes of lime, cilantro and a dollop of sour cream. All garnishes are optional and you can also add anything you choose.
Garnishes are not included in the calorie count. As always, nutrition information is only approximate. If this number is important to you, please calculate yourself using your exact weights, measurements and the brands you are using to make this.