• Make the meatball mixture. In a large mixing bowl, combine all the meatball ingredients. Mix by hand until all the ingredients are just mixed. Take care not to overmix.
• Shape the meatballs. Using a 1-2 tablespoon scoop, portion the meat mixture and roll into balls. Place them on a parchment lined baking sheet.
• Broil the meatballs. Arrange an oven rack to be near the broiler and broil the meatballs on high for 7-8 minutes, until just barely browned. Remove from the oven and set aside.
• Preheat an oven to 425ºF. Line a small baking sheet with parchment paper.
• Roast the tomatoes, then blend. Toss the quartered tomatoes and garlic cloves with 2 tablespoons of olive oil and season with salt and pepper. Pour them onto the tray and group everything together in the center (this keeps the garlic from burning!). Roast for 25 minutes, until the tomatoes are blistered. Transfer to a blender with the chile de arbol and blend until smooth.
• Build the soup base. Heat the remaining olive oil in a large dutch oven or soup pot over medium heat. Add the white onion and tomato mixture and cook for 3-4 minutes, until some of the liquid has evaporated.
• Add the meatballs and simmer. Add the chicken stock, bouillon, carrots, and potatoes to the pot and bring to a simmer. Add the meatballs, cover, and simmer for 30 minutes.
• Add the veggies. Add the zucchini and green beans to the pot and simmer for another 5-10 minutes, until the veggies are just barely tender without being mushy. Season the soup to taste with salt and pepper and stir in the cilantro. Ladle into bowls and serve with limes and tortillas on the side for dipping.

Storage Instructions

• Storage and reheating: Cool the soup to room temperature and transfer to an airtight container. When properly stored, it is good for 3-5 days. (I don't recommend freezing the soup as a whole (though you can!), because the veggies get a little weird after defrosting.) You can reheat large batches of soup on the stove over medium low heat, stirring gently until warmed through. Add additional water or broth as needed to reach desired consistency.