Place two saucepans on the stove.
In one saucepan (Pot 1), place the stock, ginger, garlic, spring onions, chili (if using), soy sauce and mirin. Stir and cover the pot. Let it come to a boil at medium high – high heat. Then lower the heat to medium and let it simmer for 25 minutes. Taste the base and add more soy sauce if needed.
While Pot 1 is simmering, add water to the second pot (Pot 2), and bring it to a boil. Add the dried noodles to the boiling water, and cook according to package directions. I prefer cooking the noodles for ONE MINUTE LESS than what’s recommended on the package, as the noodles will continue to cook for a bit longer when served with hot broth. The straight ramen noodles I use here take 3 minutes to cook. Drain the noodles and divide into 4 bowls and set aside.
When the ramen base in Pot 1 has cooked for about 20 – 25 minutes, strain to remove the garlic, ginger, chili and spring onions (or only the spring onions and chili). Add the strained stock back into the pot and add the mushrooms, and let it cook for a further 5 minutes until the mushrooms have softened. The ramen base is now ready.