Nervetti Soup

Method

1. Soak the knee bones in cold water for 40-45 minutes, changing the water twice.
2. Rinse the bones thoroughly.
3. Place the bones in a pressure cooker, cover with water, bring to a boil and skim off any impurities.
4. Close the pressure cooker, bring to pressure, and cook on low heat for 1 hour from when the cooker starts whistling.
5. Turn off the heat and let the pressure cooker cool naturally. Then refrigerate the entire pot for 12 hours.
6. After 12 hours, open the pot. The broth should be gelatinous. Return the pot to the heat, bring to pressure again, and cook for 30 minutes.
7. Turn off the heat, let cool, open the pot and remove the bones. Separate the marrow from the bones and set it aside. Also pick out any pieces of meat and cartilage (nervetti) and set them aside.
8. Strain the broth into a large pot, add about 1 liter of water to reach the desired level. Return the cleaned bones to the pot and bring to a boil. Cook for 30 minutes.
9. Meanwhile, prepare the mandatory vegetables: dice the celery, carrot, and onion into small cubes. Quarter the cherry tomatoes. Finely chop the garlic clove.
10. After 30 minutes, add the diced vegetables (celery, carrot, onion), tomatoes, garlic, a handful of salt, and some black peppercorns. Cover and cook for 20 minutes.
11. After 20 minutes, add the optional vegetables: chopped black kale, broccoli or cauliflower florets, fennel, a small piece of ginger, turmeric (fresh or powder), cumin, cloves (finely ground), and optional hot or sweet pepper. Cover and cook for another 25 minutes.
12. Remove the bones from the pot using a slotted spoon.
13. Cut the reserved meat and cartilage into bite-sized pieces. Add them to the soup and cook for 5 minutes.
14. Adjust salt and cook for another 2-3 minutes.
15. Turn off the heat, add chopped parsley, cover, and let rest for 10 minutes before serving.
16. Serve with a dollop of sour cream, a piece of marrow, and some mostarda on top.