Add the oil, onion, celery, and cabbage to a soup pot and sauté for 7-10 minutes (stop when it's starting to lightly brown).
Add in the garlic and cook for 30 seconds.
Stir in the tomato sauce, broth, carrots, potato, corn, zucchini, and Italian seasoning. Increase the heat to high and bring the soup to a boil.
Once the soup is boiling, reduce the heat to a simmer and cover with the lid slightly open. Cook for 20-25 minutes or until the potatoes and veggies are tender.
Season with salt & pepper as needed and stir in the spinach.
