Bring a large pot of salted water to a boil. Add 12 oz noodles and cook according to package instructions until just al dente (usually 3–5 minutes for fresh, 7–9 for dried). Drain and rinse briefly with warm water to remove excess starch, toss with 1 tsp sesame oil to prevent sticking, set aside.

Mix sauce

In a bowl whisk together 6 tbs low-sodium soy sauce, 2 tbs oyster sauce, 120 ml chicken or vegetable stock (or water), 1 tsp cornstarch, and 1 tsp sugar until smooth. Taste and adjust: more soy for saltiness, more stock if too thick.

Protein (choose one)

Marinate protein

Pat the chosen protein dry. Toss 10 oz sliced chicken, steak, or tofu with 1 tbs soy sauce and 1 tsp cornstarch until evenly coated. Let sit 10 minutes while preparing vegetables. This tenderizes meat and gives tofu a better sear.

Cook protein

Heat a large wok or heavy skillet over high heat until very hot. Add 1 tbs neutral oil. Add marinated protein in a single layer and sear: chicken 2–3 minutes per side until cooked through, steak 1–2 minutes per side for medium depending on thickness, tofu 2–3 minutes per side until golden. Remove protein to a plate and keep warm.

Vegetables

Stir-fry aromatics

Reduce heat to medium-high and add remaining 1 tbs neutral oil to the wok. Add 3 minced garlic and 1 tsp minced ginger and the white parts of the scallions. Stir 15–30 seconds until fragrant; do not burn.

Cook vegetables

Add 1 cup sliced cabbage, 1 cup julienned carrot, 1 cup chopped bok choy or napa (if using), and 3 oz snow peas. Stir-fry 2–3 minutes until vegetables are bright and just tender-crisp. Season with 1/2 tsp salt and 1/4 tsp pepper. If using chili flakes, add now.

Finish & Combine

Return the cooked protein to the wok with the vegetables. Toss to combine for 30 seconds.

Add the cooked noodles and pour the prepared sauce over everything. Using tongs or two spatulas, gently toss and stir for 1–2 minutes so the sauce evenly coats the noodles and ingredients. If the mixture seems dry, add 1–2 tbs additional stock or water.

Cook until sauce thickens slightly and everything is heated through, about 1–2 minutes. Taste and adjust seasoning with extra soy sauce or salt if needed.

Turn off heat and drizzle 1 tsp sesame oil over the lo mein, toss in the green parts of the sliced scallions, and sprinkle with sesame seeds if using. Serve immediately with lime wedges on the side.