Soak the rice in water for 20 minutes, rinse and drain. In a large bowl, mix all the meatballs ingredients just until everything is combined (do not over mix) then chill for at least 10 minutes in the fridge. Use a cookie scoop to grab some raw meat then gently roll between your hands to make perfectly-sized uniform meatballs.
Heat oil in a large Dutch oven at medium heat. Sauté onion for 4 minutes, add serrano peppers and cook for 1 minute. Add garlic and cook until fragrant.
Add carrots, and diced tomatoes. Stir for 2 minutes.
Add chicken broth, water, potatoes, and meatballs. Bring the soup to a boil then reduce the heat, cover, and simmer for 15 minutes.
Add zucchini and simmer for another 15 minutes or until the veggies are tender.
Adjust seasoning with salt, black pepper, or a dash of cayenne pepper if needed.