Soak the mushrooms in 2-3 cups of hot water for 20-30 minutes (until plump), then remove the mushrooms from the water with a slotted spoon and reserve 1 cup of the liquid.
Slice the fresh mushrooms and set aside.
In a large saucepan, heat the chicken stock and bring to a boil.
Add the green onions, soy sauces, oyster sauce, mushrooms, mushroom liquid, and the noodles. Return to a boil.
Reduce the heat and cook according to noodle package instructions (just until tender).