I was shocked to see I hadn't posted this soup, which is one of my stand-by favorites. It's similar to 'Italian Wedding Soup', but I leave out the pasta and I call it Roman because it contains ingredients that the Romans would have had before contact with the Americas.
A big batch of meat broth, ~6-8 cups
A pound of ground meat, I like to combine turkey and beef
1 large onion
1 clove garlic
Fresh parsley, ~1/2 c. chopped finely
2 cups blanched kale, chopped (or other greens: see below)
Salt and pepper
A dash of white wine vinegar
Grind 1/2 of the onion and the garlic in a food processor or chop it very finely--almost pureed. Combine it with the meat and parsley and form into tiny meatballs. Bring the broth to a boil and drop the meatballs in, gently making sure they don't stick to the bottom. When they rise to the top, cover the pot and simmer for 10 minutes. Add the onions, kale, and seasonings and simmer 5 more minutes. Go heavy on the black pepper--the Romans loved that stuff.
You can spice this more if you like, but I like to keep it simple. Don't add the kale raw or it will make the soup too bitter. You can use any other greens that you like, and the more tender ones won't need to be blanched. I like escarole or kommatsuna for this soup too.