Pour the chicken broth into a medium pot, and add the ginger, turmeric, garlic and fish sauce. Bring to a boil, then reduce to a simmer for 20 to 30 minutes to really infuse the broth with flavor. Note: If using turmeric powder (ground turmeric), start with ¼ teaspoon (0.5 gram), and increase to ½ teaspoon (1 gram), depending on your preference. I find turmeric powder to be insanely potent, much more so than the fresh root, so always add less and bump it up if you’d like. While the broth is simmering, prepare the rest of the ingredients.
Using a slotted spoon, remove the ginger, turmeric and garlic. Discard. Or, if you like to live dangerously, leave it all in the soup and pick around it while you’re eating (like I did in the photo). Just be aware: Biting into a large chunk of ginger, turmeric or garlic is usually not pleasant.
Add the chicken, mushrooms, green onions, carrot and if desired, your noodles. Heat about 5 minutes on medium-low or until everything is warmed through. Taste and adjust the seasoning with sea salt.