While meatballs are baking, prepare the soup. In a large dutch oven over medium heat, drizzle the olive oil. Once the oil shines, it’s hot. Add all of the diced onion, carrot, and celery. Saute for 5-8 minutes or until the vegetables are getting golden. Then, add garlic and fresh herbs and saute for 2 minutes more. Do not let the garlic burn! But you do want there to be a little bit of browning on the bottom of the pan. That is called fond, and it will give your batch of soup incredible flavor.
Now that the vegetables are browned and there is some browning on the pan, de-glaze the pan with the dry white wine or vinegar. Add the wine/vinegar, and using a wooden spoon, scrape up all the brown bits on the bottom of the pan as the wine helps you remove them. Let it come to a boil for just a minute while you do this. Add your salt and pepper. Then add all of the beef and chicken stock.
Let this mixture come to a simmer, and then add the meatballs and the caulifower rice.
Add the thinly sliced kale. The recipe calls for 8-10 cups because I love it when my soup is full of greens, but feel free to adjust this amount.
Let this soup simmer for at least 30 minutes, but it certainly can simmer for longer. I’ve let it simmer all afternoon at times and it’s so delicious by dinner. The flavors meld over time and develop further.
When ready to serve, top each bowl with a sprinkle of good Parmigiano Reggiano or more fresh herbs. Enjoy!