2) Meanwhile, in a large non-stick frying pan over high heat, melt the butter. Add the sliced fresh mushrooms and cook until crisp and brown, about ten minutes. Season with salt and pepper, to taste, and distribute them evenly between four soup bowls.
3) Put the eggs in a small saucepan and cover with cold water. Bring to a boil, turn off heat, cover, and let cook until almost soft boiled, three to four minutes. Immediately rinse the eggs with cold water and set aside.
4) Strain the mushroom stock. Return to the pan and heat. Season with the sherry, soy sauce and salt to taste. Divide noodles, enoki mushrooms, if using and spring onions evenly in each soup bowl.
5) Crack a soft-boiled egg into each bowl (to maintain the egg's shape, peel them carefully, or use as small spoon to free them from the shell). Ladle 500ml of hot broth into each bowl. Sprinkle gomashio or shansho pepper over the soup, if desired, and serve immediately.