Cut the beef into thin slices about 1/4 inch thick ( see NOTE #1). Place them in a bowl then add apple cider vinegar or white vinegar, soy sauce, cornstarch, and baking soda. Toss to coat the beef with the marinade. Let it sit for 5 minutes.
MAKE THE SAUCE: In a bowl or measuring cup, add soy sauce, oyster sauce, apple cider vinegar, brown sugar, honey, and cornstarch. Stir until the sugar and cornstarch dissolve.
Meantime, cook the noodles. Follow the instructions on the back of the package. Or boil water, add the noodles, and cook for 2 minutes or al dente. Reserve 1/4 cup of noodle water for later when stir-frying the veggies. As soon as the noodles are cooked, run them in cold water to stop the cooking process and prevent them from sticking. Do not overcook the noodles or they will turn mushy. Set them aside.
Heat the wok or wide pan with oil. Cook the beef in batches, do not overcrowd the pan. Sear them for 2 minutes or until golden brown. Remove from the pan and set them aside.
Use the same pan, add more oil if the pan is drying. Saute the onion for 2 minutes or until tender. Add garlic and ginger, and continue sauteing until fragrant.
Add the rest of the vegetables except cilantro and green onions. Stir until well combined. Pour the reserved noodle water to help cook the veggies (see NOTE #2).
Add the cooked noodles and beef, and stir the sauce before adding to the pan. Toss and make sure the noodles are coated well with the sauce. Add sesame oil and red chili pepper flakes. Garnish with cilantro and green onions.