Combine all the meatball ingredients, roll into 1½ inch balls, and set aside.
Heat oil in a 6 quart or larger pot over medium heat.
Add onions, carrots, and celery. Sauté until softened.
Add garlic, chili powder, oregano, and paprika, and stir together, cooking for 30 seconds or so.
Stir in the potatoes and rice.
Add diced tomatoes, green chilis, and beef broth, and stir together.
Carefully add the meatballs and bring to a simmer.
Simmer for about 15 to 20 minutes until the meatballs are cooked through.
Add zucchini, and bring back to a simmer until rice and vegetables are all tender.
Serve with preferred toppings.