This soup starts with water rather than broth but cooking the meatballs and greens provides all the flavor you need.
1/2 an onion, chopped into large pieces
2 cloves garlic, chopped into large pieces
1 stalk celery, chopped into large pieces
1 carrot, peeled and chopped into large pieces
2 Tbsp. dried basil or 5 fresh basil leaves
1/4 tsp. dried red pepper flakes (pepperoncino)
1 Tbs salt, divided
3 Tbsp olive oil
3 quarts cold water
1 zucchini, cut in half lengthwise and then cut into 1/2” chunks
2-3 cups kale, cut in slices
2-3 cups spinach, cut in slices
1/2 pound ground pork
1/2 pound ground beef
1/2 cup bread crumbs
1/2 cup shredded Parmesan cheese
1 eggs, beaten
1 Tbsp. dried parsley or 2 Tbs fresh chopped parsley
Put the onion, garlic, celery, carrot, basil, pepperoncino and 2 tsp. salt in a food processor and pulse until fine.
In a large skillet or soup pan, heat the olive oil until hot and then add the minced vegetables. Cook, stirring, about ten minutes.
Add the water and bring to a boil, then reduce the heat to a simmer. Cover and simmer 20 minutes.
Add the zucchini, 1 tsp. salt and cover again, the simmer for 20 more minutes.
Add kale (or escarole) and spinach (or all escarole or kale or spinach). Uncover and simmer until the liquid has reduced by 1/3, about 30 to 40 minutes, stirring periodically.
In the meantime, make the meatballs by combining the ground meats, bread crumbs, cheese, parsley, egg and salt in a large bowl. Mix with your hands until well combined the form into 1” (golf ball size) balls. You can make them smaller if you'd like. It just takes more time and I get impatient!
After the greens have cooked and the liquid has reduced, add the raw meatballs and cook another 20 minutes, until cooked through.