Lo Mein is a Cantonese dish meaning "stirred noodle". Traditionally Lo Mein is a variation of wonton noodles where all the components including the noodles are served separately. Lo Mein in Mandarin is known as "Ban Mein" i.e. mixed sauce noodle and not necessarily stir fried together, just tossed together. This makes for a simple satisfying supper great as a family sharing plate with other dishes. Don't be phased by what seems like a long list of ingredients - pre-cook the noodles, combine the ingredients for the sauce. Stir-fry the main ingredients and toss the noodles and ingredients in the sauce. To ensure the shrimp does not get overcooked, ensure the ingredients are added in quick succession in the wok and that all the ingredients are pre-chopped.
For the sauce: Mix together the stock, 3/4 cup water, the cornstarch and soy sauce. Stir well and set aside. For the noodles: Bring a pot of water to a boil, and then add the noodles and cook until al dente, 3 minutes. Drain under cold running water. Add the sesame oil to prevent the noodles from sticking together.
Heat a wok over high heat and add the peanut oil. Add the ginger, mushrooms and garlic and toss together for a few seconds. Then add the shrimp and cook, stirring, for less than 1 minute. Add the choi sum leaves and toss together for 1 minute. As the shrimp starts to turn pink, add the Shaosing rice wine.
Pour in the sauce and bring to a boil; this will take 1 to 2 minutes. Quickly add the cooked egg noodles and season with the sesame oil and dark soy. Stir together well for 1 minute, making sure all the noodles are coated in the sauce. Season the ground white pepper and transfer to a serving bowl. Serve immediately.
If using dried shitake mushrooms, you can use the steeping water to soften the mushrooms instead of vegetable stock.