Remove tails from shrimp if you wish or leave them on for extra flavor. Mix the marinade ingredients in a bowl, add the shrimp and marinate for at least 20 minutes.
Instructions for preparing the lo mein noodles will be on the package. Be sure to have the noodles prepared and cold drained before your are ready to stir fry.
Prepare stir fry sauce in a measuring cup. Mix well. Taste it and adjust the heat level to your preference. Set aside.
Fill a small sauce pan with water and boil. Blanch the snow peas for about 30 seconds, till they turn bright green. Immediately cool them off in a colander under cold water. Set aside.
Heat a wok over medium heat, do not add oil until the wok starts to shimmer. Tilt wok to coat hot oil all over. Add shrimp. Cook for a minute, then turn the shrimp over using chopsticks or tongs. When the shrimp have barely turned pink, remove and set aside.
Turn the flame up a bit and depending on the cook you like of the vegetables you can add mushrooms or peppers first or at the same time. Stir constantly.
When the vegetables are nearly cooked, return the shrimp to the wok, cook for a minute or two to cook through. Add the well mixed stir fry sauce. Stir and add the noodles. Tongs are useful at this point to spread noodles out and incorporate them into the vegetables and sauce. Toss in snow peas and scallions, stir and serve.