Cook the noodles: Boil according to package directions until just tender.
Drain and rinse under cold water to stop the cooking. Toss with a little oil to prevent sticking.
Mix your sauce: In a small bowl, combine soy sauce, oyster sauce (if using), sugar, and a few grinds of pepper. Taste and adjust—aim for savory with a hint of sweetness.
Heat the pan: Set a large skillet or wok over medium-high heat.
Add 1 tablespoon of oil and let it shimmer.
Scramble the eggs: Beat the eggs with a pinch of salt. Pour into the hot pan and scramble gently until just set. Remove to a plate.
Stir-fry aromatics: Add the remaining oil.
Toss in garlic and the white parts of the scallions (or onion). Stir 30–45 seconds until fragrant, not browned.
Add the vegetables: Stir-fry 2–3 minutes until crisp-tender. If using cabbage or bean sprouts, add them toward the end so they stay crunchy.
Noodles in: Add the drained noodles.
Toss well so they warm through and separate. Let them sit for 20–30 seconds to get a little sear before tossing again.
Sauce it up: Pour the sauce around the edges of the pan so it sizzles. Toss repeatedly until the noodles are evenly coated.
Return the eggs: Add the scrambled eggs back in.
Break them into bite-size pieces and mix gently.
Finish and season: Add the green tops of the scallions, drizzle with sesame oil, and adjust with pepper, chili oil, or a tiny squeeze of lime. Serve hot.