Start by filling a large pot with plenty of water and bring it to a full rolling boil so the noodles can cook quickly without sticking. While the water heats, measure the soy sauce, oyster sauce and sugar into a small bowl and stir until the sugar dissolves, creating a smooth, glossy base for the lo mein sauce.​​

Once the water boils, add the Chinese egg noodles and cook them according to the package directions; for many brands this will be around 3 minutes, just until they are tender but still pleasantly chewy. Avoid overcooking at this stage because the noodles will spend another minute or two in the hot pan and should stay slightly firm so they do not turn soft when tossed with the vegetables.

As soon as the noodles are done, drain them well and set them aside while you finish the stir fry, keeping them nearby so they can be added as soon as the vegetables are ready. If they seem to stick a little as they sit, use clean tongs to gently loosen and separate them before they go into the pan to help them coat evenly with the sauce later.​​

Place a large skillet or wok over high heat, giving it a moment to get thoroughly hot before adding anything so the vegetables sear instead of steaming. Pour in the vegetable oil and let it heat until it becomes lightly smoky, which signals that the pan is hot enough to give the noodles and vegetables that classic stir fry flavor.​​

This very hot oil helps the aromatics release their fragrance instantly, so resist the urge to lower the heat at this stage; the quick contact with high heat is what keeps the vegetables crisp tender. Swirling the pan gently to coat the surface with oil also helps prevent any sticking when you add the onions, ginger and mushrooms.​

Add the sliced onion and chopped ginger to the hot, oiled pan along with the sliced shiitake mushrooms and matchstick carrots, tossing everything quickly so it is coated in the shimmering oil. Stir fry this mixture over high heat for about 3 minutes until the onions soften slightly, the mushrooms release a bit of their moisture and the carrots start to become tender while still holding some crunch.​​

Keep the vegetables moving by stirring and flipping them frequently so they cook evenly and do not scorch in the hot spots of the pan. The goal here is to build a flavorful base with the sweet onion, bright ginger and earthy mushrooms, which will cling to the noodles later and give each bite more depth.​

During this stir fry time, check that the noodles are drained and the sauce is ready so you can move smoothly into the next step without pausing and losing the heat in the pan. If at any point the pan looks very dry and the vegetables seem to catch, you can add a very small splash of water to create a little steam while keeping the heat high.​

Once the vegetables have sautéed for a few minutes, add the drained egg noodles directly into the pan, using tongs to gently lift and separate them so they combine with the onions, mushrooms and carrots. Scatter the quartered baby bok choy over the top, positioning some of the white stems against the bottom of the pan so they have a chance to soften while the leafy tops wilt.​​

Pour the prepared mixture of soy sauce, oyster sauce and sugar evenly over the noodles and vegetables, then toss everything together so the sauce coats each strand of noodle and every piece of vegetable. Cook this mixture for about 1 to 2 minutes, just until the bok choy is wilted and tender but still vibrantly green and the noodles are glossy from the absorbed sauce.​​

Use a lifting and folding motion with tongs rather than aggressive stirring, because this keeps the noodles intact and distributes the sauce more evenly throughout the pan. As the sauce heats, it will cling to the noodles and slightly thicken, creating a savory, slightly sweet coating that ties the dish together without becoming heavy.​

In the last 30 seconds of cooking, add a generous handful of bean sprouts to the wok, scattering them over the top of the noodles so they barely soften in the residual heat. Quickly toss once or twice just to mix them through, then remove the pan from the heat so the sprouts retain their fresh crunch and the vegetables do not overcook.​​

This final addition of crisp bean sprouts gives the finished lo mein a bright, juicy texture contrast and a light, fresh flavor that balances the richness of the soy and oyster sauce. Serve the veggie lo mein immediately, piling the noodles into warm bowls so the steam carries the aroma of ginger, mushrooms and bok choy to the table.​