Warm a medium soup pot, Add the cinnamon sticks, cloves, and star anise and toast until fragrant, stirring occasionally, about 3 to 4 minutes. Add the onion, ginger, vegetable stock, water, and tamari. Raise the heat to high and bring the mixture to a boil, then reduce the heat as necessary to maintain a gentle simmer. Simmer for 30 minutes to give the flavors time to meld.
Prepare your rice noodles by cooking them according to package directions. Set them aside.
To prepare the shiitake mushrooms, warm the oil in a medium skillet over medium heat until shimmering. Add the mushrooms and a few dashes of salt. Cook until the mushrooms are tender and lightly browned, about 4 to 6 minutes, then set them aside.
Once the broth is done cooking, strain out the onions, ginger and spices (this is easiest with a small metal sieve, but you can also strain the mixture through a colander into another large bowl). Season it to taste with extra tamari and/or salt until the flavors of the spices really shine.
Ladle the broth into bowls, add cooked noodles and mushrooms, and fresh garnishes
