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.
Serve with more grated cheese.