Heat the oil in a nonstick skillet over medium heat. Add the onion and garlic and sauté until golden.
In a blender, purée the onion, garlic, peppers, and half the can of tomatoes.
Transfer the purée, along with the remaining half can of crushed tomatoes and the broth, to a large pot. Bring to a boil. Lower the heat and simmer, uncovered, stirring occasionally, for 20 minutes.
Meanwhile, heat the oil for frying in a heavy pot over medium-high heat or in a deep-fryer (you could even bake them with just the salt). Add the tortilla strips and fry until golden brown. Transfer the strips to a paper-towel-lined plate and sprinkle with salt.
Just before serving, add 2 teaspoons salt and the lime juice to the soup and stir. Divide the avocado chunks into four soup bowls, ladle the soup over them, and garnish each with 1 tablespoons nondairy sour cream, fried tortilla strips, green onions, and cilantro. Serve immediately.