To make the meatballs: Char chiles over direct flame or in broiler until blackened on all sides. Enclose in paper bag or in a bowl covered with plastic wrap and steam 10 minutes. Stem, seed, and peel chiles, then chop finely (should yield about 3/4 cup). Place chiles in large bowl, and gently mix in beef and all remaining ingredients. Roll meat mixture into 1-inch meatballs.
To make the soup: Heat oil in large pot over medium heat, and add onion with any juices and garlic. Sautxe9 until onion is tender, about 3 minutes. Add chile powder and cumin and stir 1 minute. Add broth and oregano; bring to rolling boil. Reduce heat to very low, just below bare simmer, and cook 10 minutes.
Stir zucchini and rice into broth. Increase heat to medium and drop in meatballs, 1 at a time. Return soup to simmer. Cover and cook gently until meatballs and rice are cooked through, stirring occasionally and adjusting heat to avoid boiling, about 20 minutes. Add 1/4 cup cilantro and 1 tablespoon lime juice. Season soup with salt and add more lime juice, if desired.
To make tortilla strips: Preheat the oven to 425. Arrange strips on a baking sheet and spray with oil or toss with a little canola oil (and salt, if desired). Bake for about 8-10 minutes, or until crispy.