Remove casing from sausage and sauté over medium high heat until browned. Remove from pot and set aside letting fat drip off. Remove all but 1 Tbsp of fat in pot.
Add onion, celery, carrots and cook until slightly softened, 3 to 5 minutes. Add garlic and cook another minute. If pot is too dry, add a little water to prevent burning. Stir frequently.
Add seasoning and cook just to release aroma, 30 seconds.
Add tomato paste, canned tomatoes, soup stock and lemon juice or vinegar. Scrape off any browned bits from bottom of pot. Bring to boil. Reduce heat, add bay leaf and Parmesan rind (if using), cover and simmer until vegetables are almost tender, 10-15 minutes.
Add tortellini and diced sweet peppers and cook another 5 minutes.
Add spinach and let simmer for another 3 minutes.
Remove from heat. Add some of the liquid from the hot soup into the cream or evaporated milk to temper it. Removing from heat and heating the dairy will prevent it from curdling.
Taste and adjust seasoning. Remove bay leaf and Parmesan rind.
Garnish with celery leaves, parsley, dill or chopped green onions.
