For the meatballs:

In a large bowl, combine the ground beef, ground pork, eggs, and breadcrumbs.

Blend the garlic cloves, parsley, and milk together in a blender until smooth, then add to the bowl.

Mix everything together very well. Season with salt and pepper to taste. Let the mixture rest in the refrigerator overnight for best flavor, or for at least 1 hour if making the same day.

Pour some vinegar onto one plate and flour onto another. Moisten your hands with vinegar to prevent the meat from sticking, then take portions of the mixture and shape into balls. Roll each meatball in flour, then fry them until just cooked through but not browned. Set aside on a plate. Don’t overcook them—they should be just done, not golden brown.

For the sauce:

In the same oil used to fry the meatballs, sauté the finely chopped onion and garlic for a couple of minutes. Add the peeled and diced carrot, sprinkle with a pinch of salt, and cook together until the onion turns translucent.

Meanwhile, wash, seed, and dice the bell peppers. When the onion is ready, add the peppers and cook for a couple more minutes.

Add the cleaned and quartered mushrooms. Stir well and cook everything together over low heat for 15 more minutes.

Grate the tomatoes. After the 15 minutes, add the grated tomato and green peas. Mix well and cook for another 15 minutes, until the tomato has lost its liquid and is cooked down.

Once the vegetables are tender, add the meatballs to the pot and pour in enough beef broth to cover them. Stir so the broth mixes with the vegetable sauce and cook for 5 more minutes. Cooking for 5 minutes will keep the meatballs very tender; cooking longer may make them tough.