For a more substantial soup, divide 2 cups shredded, cooked chicken among the serving bowls before adding the hot broth, avocado, and garnishes.
Heat a medium cast-iron or other heavy skillet over medium heat. Place in the skillet:
Roast in the skillet, turning occasionally, until the peppers are blistered and blackened on all sides, the onion quarters are charred, and the garlic is soft to the touch, 10 to 15 minutes. Once cool, seed and stem the peppers, peel the garlic, and transfer to a blender. Set the onions aside. Add to the blender:
Blend to a smooth puree. Heat in a soup pot over medium-high heat:
Add the tomato puree to the pot and cook, stirring, until the mixture has darkened and slightly thickened, about 5 minutes. Dice the reserved onion and add to the pot, then add:
Simmer, stirring occasionally, for 15 minutes. Meanwhile, have ready:
Or heat to 365°F in a heavy skillet:
Cut into ¼-inch-wide strips:
and fry in the oil until crisp. Drain on paper towels and set aside. Season the broth to taste with:
Divide half of the chips or fried tortilla strips among serving bowls and ladle the broth over them. Top with the remaining tortilla pieces and garnish with: