In large pot, combine water, bay leaf, half of onion, green pepper, and 1/2 teaspoon of mint. Bring to boil.
In bowl, combine chicken, beef, other half of onion, tomato, oregano, corn flour, pepper, garlic, and salt. Mix well. Form 1-inch meatballs. Place meatballs in boiling water and lower heat. Cook over low heat for 30–45 minutes.
Add carrots, chayote, cabbage, and celery. Cook over low heat for 25 minutes. Add corn and zucchini. Cook for another 5 minutes.
Garnish with cilantro and rest of mint.
There are 154 calories in 1 serving of Meatball Soup.