Combine the tomatoes, tomato paste, garlic, serrano chiles, oregano, cumin, and 2/3 teaspoon salt in blender or food processor and puree.
In large stock pot, combine chicken stock, beef broth, potatoes, carrots, onion, bok choy, celery, green beans, okra, pureed tomato mixture, salt and pepper. Bring soup to a simmer and cook 20 to 30 minutes, adding additional stock if needed. At end of cooking time, add lime juice (or balsamic vinegar).
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