To make this soup, start by heating a large pot or dutch oven, on the stove, over medium heat. Then, add in the olive oil.
While the oil is heating up, chop and prepare the onions and garlic. Then, once the pan is hot, add them into the pan alongside the Italian seasoning, chili flakes, sea salt, and ground black pepper. Sauté them for about 5 minutes, until the onions begin to soften.
Once the onions have softened, add the Italian sausage to the pan, being sure to remove the casing before adding it in. Use a wooden spoon to break the sausage up into smaller pieces and allow it to cook until it's browned.
Next, add in the arrowroot starch, tapioca flour, or cornstarch if using, alongside the diced potatoes, chopped kale, chicken broth, heavy cream or non-dairy milk, and grated parmesan cheese. Stir until the mixture reaches a gentle boil.
Once the soup is boiling, reduce the heat to low, cover the pot, and allow the soup to cook for an additional 15 minutes.
Finally, once the soup is done, squeeze lemon juice over the top and add in another serving of parmesan cheese. Then, serve the soup and enjoy! Store any leftovers in a mason jar in the fridge for up to one week.