Start by sauteing, medium to high heat, the onion, garlic, carrots, celery, and mushrooms, seasoned by adding soy sauce and black pepper, also while adding a small amount of water to the pot so that the ingredients do not stick on the bottom of the pot, and until they are cooked to a golden brownness and also being softened.
Add water into the pot, with all the ingredients still in it, until the pot is 3/4ths full and start boiling the soup.
Add cayenne pepper, turmeric, garlic powder, nutritional yeast,, and mushroom seasoning powder to the soup.
Once the soup has been brought to a boil, add the whole wheat spaghetti noodles and cook until al dente.
Bring the heat down to a simmer and add in the green onions and miso paste.