Start the soup by cooking the Italian sausage in a Dutch oven or large stock pot on medium-high heat.
Immediately, add 1 tsp of salt to the Italian sausage and use a wooden spoon to mix the salt into the Italian sausage.
Once the sausage is cooked, remove all but 1-2 tablespoons of rendered pork fat.
Next, add the diced onion to the cooked Italian sausage, and add ½ tsp of salt. (The salt is added throughout the recipe to season each ingredient and build the flavor.)
Now add ½ of the minced garlic. Saute the garlic for a couple of minutes. Keep the garlic moving in the pan so as not to burn the garlic.
Then, add the carrots, zucchini, ½ tsp of salt, 1 tsp of pepper, and ½ tsp of granulated garlic or garlic powder.
Add the herbs, you can tie the herbs up with food-grade butcher's twine, or just place them loosely on top of the vegetables. I recommend thyme, parsley, sage, oregano, or whatever herbs you have on hand. Thyme is the most important herb, if you were to only add one herb, thyme would be the best.
Add 6 cups of chicken stock/broth.
Add a piece of parmesan rind to the soup, this is a very important step/ingredient for the final flavor of the soup.
slow simmer soup to intensify the flavor
Bring the soup to a boil and then reduce the heat to medium-low. Simmer on medium-low for 30 mins to 1 hour keep the lid mostly on (so the steam can escape and the liquid doesn't boil over, but on enough to not lose too much of the liquid). Allow enough cooking time to soften vegetables and bring all the flavors of the soup together. (An alternative to stove-top simmering is to place the soup in the oven at 325℉ for 30 minutes to 1 hour with the lid on.)
*If you choose to add ¼ cup of uncooked jasmine or arborio rice, add it in the last 25 minutes and adjust the liquid as needed.*
While the soup is simmering, cook mushroom skulls separately to achieve maximum flavor.