Start by combining the meatball ingredients in a bowl. Mix well and cover with plastic wrap. Refrigerate. (Refrigerating the mixture will make it easier to form the meatballs.)
Heat oil in a soup pot. Add onions, garlic, and leek and sauté until softened. Add green pepper and salt. Continue to sauté until vegetables are starting to brown.
Add carrots, celery kohlrabi and zucchini, and sweat vegetables for about 5 minutes, mixing continuously.
Add chicken stock to cover (or water and consomme) vegetables and bring to a boil. Cook until vegetables are softened, about 30 minutes.
While soup is cooking, start working on the meatballs. Form small balls and fry in a bit of oil, in batches. Make sure all sides are browned. Once fried, transfer meatballs to a plate lined with paper towels to absorb excess grease.
Once soup vegetables are softened, add a can of diced tomatoes, and rinsed cannellini beans. Season and bring back to a simmer. Add meatballs to the pot. Let simmer for about 5-10 minutes just until meatballs are warmed through. Turn off heat and add a handful of fresh spinach to the soup. The spinach will wilt and soften. Serve soup and meatballs, enjoy!
Notes
This soup freezes well. Some liquid might get absorbed with cooking and you might need to add liquid once reheating.