Add the ground beef, uncooked white rice, egg, finely diced onion, minced garlic, chopped cilantro, cumin, oregano, salt, and black pepper to a large bowl.

Using clean hands or a fork, gently combine the ingredients.

Mix only until everything is evenly distributed.

Avoid aggressively working or compacting the beef, which can result in firmer meatballs.

Step 2: Shape the Meatballs

Shape the mixture into approximately 1 1/2-inch meatballs.

Place them on a clean plate as you work.

Try to make them relatively uniform so they cook at roughly the same rate.

Set the meatballs aside while you prepare the broth.

Step 3: Sauté the Onion

Heat 2 tablespoons olive oil in a large Dutch oven or soup pot over medium heat.

Add the diced yellow onion.

Cook for approximately 4 to 5 minutes, stirring occasionally, until the onion has softened.

Step 4: Add the Garlic

Stir in the three minced garlic cloves.

Cook for approximately 30 seconds, just until fragrant.

Avoid letting the garlic brown excessively.

Step 5: Cook the Green Chiles, Tomatillos, and Tomatoes

Add the chopped roasted green chiles, tomatillos, and Roma tomatoes.

Cook for approximately 5 to 6 minutes, stirring occasionally.

The vegetables should begin softening and releasing their juices.

Step 6: Blend the Green Chile Base

Carefully transfer the cooked vegetable mixture to a blender.

Add approximately 1 cup of the broth.

Blend until mostly smooth.

For a more rustic, chunky caldo, pulse the blender briefly rather than completely puréeing the mixture.

Use appropriate caution when blending warm ingredients.

Step 7: Build the Broth

Pour the blended green chile mixture back into the soup pot.

Add the remaining broth and 2 cups water.

Stir in the cumin, oregano, bay leaf, salt, and black pepper.

Bring the mixture to a gentle simmer.

Step 8: Add the Meatballs

Carefully lower the prepared meatballs into the simmering broth one at a time.

Try to distribute them evenly throughout the pot.

Avoid vigorous stirring immediately after adding them. The meatballs are still delicate and need several minutes of cooking before they firm up.

Step 9: Simmer the Meatballs

Partially cover the pot and simmer the meatballs for 20 minutes.

Keep the soup at a gentle simmer rather than a vigorous boil.

During this time, the meatballs begin cooking through and the rice inside them starts becoming tender.

Step 10: Add the Potatoes and Carrots

Add the potato chunks and sliced carrots.

Continue simmering for another 15 minutes.

The potatoes and carrots require more cooking time than the zucchini, so they’re added first.

Step 11: Add the Zucchini

Stir in the zucchini half-moons.

Cook for another 10 to 12 minutes, or until the zucchini, potatoes, and carrots are tender and the meatballs are fully cooked.

Step 12: Remove the Bay Leaf

Find the bay leaf and remove it from the soup.

Discard it before serving.

Step 13: Add Cilantro and Lime

Stir in the 1/2 cup chopped fresh cilantro and 1 tablespoon fresh lime juice.

Taste the broth and adjust the salt or green chile flavor if needed.

Adding these ingredients near the end preserves their fresher flavors.

Step 14: Serve

Ladle the hot caldo into bowls, making sure every serving gets plenty of meatballs, potatoes, carrots, zucchini, and flavorful broth.

Serve with additional fresh cilantro, lime wedges, sliced avocado, and warm corn tortillas.