Brown sausage in a large soup pan or dutch oven over med to med/high heat
Add onions and garlic and cook until soft adjusting heat so they don't burn
Poor in beef stock, ketchup, diced tomatoes and extra water.
Add carrots, celery (if using) and Italian seasoning and bring to gentle boil. You can also add spinach at this time if you use it. Wait to add zucchini until the last 15 min of the cooking time so it doesn't get too soft.
Cook until vegetables are soft.
Add more water if needed as it boils off
Adjust seasoning with salt and pepper as needed (the salt from the sausage and stock is often enough)
Either cook tortellini separate and add to each bowl (this is good for leftovers so it won't get mushy) or you can throw it in the soup and let it cook through.
Serve with parmesan cheese on top