Mix all the ingredients for the seasonings and set aside
Bring a large pot of water to a boil. Blanch the fresh egg noodles in the boiling water for 1 minute or less. Don't overcook the noodles. If you use dried noodles, cook them according to instruction. I suggest to cook it to al dente and then refresh with cold water
Preheat a wok or large skillet until really hot. Add 3 Tbsp of oil. Add the blanched noodles to the wok. Spread it on the wok as thinly as possible and let them fry until certain spots get slightly charred and crispy. Flip over and let it crisp up on certain spots. Drizzle with a bit of oil on the side if necessary. Dish out the noodles.
Preheat the wok again. Add 1 Tbsp of oil and add onion slices. Usually, yellow/white onions are used, but I only have purple onion and that's what I used. Stir fry until they are slightly softened but still has a bit of crunch. Add the noodles followed by the seasonings. Toss to mix everything and to make sure the seasonings coat the noodles. Add beansprouts and stir fry for about 30 seconds or so or until it just a bit soft but still have that crunch. Have a taste and adjust by adding more soy sauce if needed. Turn off the heat and serve immediately