Cook noodles in boiling water according to package instructions. When cooked, drain the water, and then run noodles under cold tap water to stop the noodles from further cooking. Set aside.
Heat oil in a frying pan on medium fire, then toss in dried red chili peppers, and sauté for a minute until the chili infuses the oil (the oil should smell spicy). Skip the dried red chili peppers if you do not want the dish to be spicy.
Add in garlic, young galangal, and yellow onion, and sauté for another minute or until the onion slices soften.
Add in the mushrooms, light soy sauce, rice wine vinegar, and oyster sauce (if using). Sauté until mushrooms are cooked and tender, about 2-3 minutes.
Continuing on medium fire, add in the cooked noodles, and quickly stir to combine all the ingredients. Then season with black pepper and dashes of sesame oil.
Turn off heat. Serve noodles in individual bowls and garnish with spring onion and fresh red chili peppers.