Bring a large pot of water to a boil over high heat. Add the noodles and boil for 2 minutes. Drain the noodles in a colander and rinse well with cold running water. Place in a bowl, add 1 Tbs. of the corn oil and toss to coat evenly.
In a small bowl, combine 3 Tbs. water, the oyster sauce, soy sauce, vinegar, sesame oil and sugar and stir to dissolve the sugar.
Stir-fry the vegetables.
Heat a wok or large fry pan over high heat until very hot and add 2 Tbs. of the corn oil. Add the onion and bell pepper and stir-fry just until tender, about 2 minutes. Add the mushrooms and zucchini and continue to stir-fry until golden brown, about 2 minutes. Using a slotted spoon, transfer the vegetables to a bowl.
Stir-fry the noodles.
Return the pan to high heat and add the remaining 2 Tbs. corn oil. Add the ginger and garlic and stir-fry until fragrant, about 5 seconds. Add the noodles and cook until heated through, about 5 minutes. Return the vegetables to the pan, add the sauce, and continue to stir and toss until all the ingredients are well combined and heated through, about 1 minute. Transfer to a platter and serve immediately. Serves 4.