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 when you start to stir fry.
Prepare stir fry sauce in a 1-2 cup measuring cup. Mix well. Taste it and adjust the heat level to your preference. Set aside.
Heat the oil in a wok over medium heat. Wait till pan shimmers before adding 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.
Add all the vegetables except scallions to the wok and turn the heat up a little. Depending on the cook you like of the vegetables you can add mushrooms first, then peppers and lastly snowpeas.
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 scallions, stir and serve.