Cook the noodles: Bring a large pot of salted water to a boil.
Cook noodles until just shy of tender (1–2 minutes less than package time). Drain, rinse briefly to stop cooking, and toss with a drizzle of oil to prevent sticking.
Make the sauce: In a bowl, whisk soy sauce, oyster sauce, dark soy, hoisin, rice vinegar, brown sugar, broth mixed with cornstarch, pepper, and chili if using. Set aside.
Prep the shrimp: Pat shrimp dry.
Season lightly with salt and pepper. Dry shrimp sear better and stay juicy.
Heat the pan: Set a large wok or skillet over medium-high heat. Add 1 tablespoon oil.
Sear the shrimp: Add shrimp in a single layer.
Cook 1–2 minutes per side until just pink and opaque. Remove to a plate. Do not overcook.
Stir-fry the aromatics: Add 1 tablespoon oil.
Add garlic and ginger. Stir 20–30 seconds until fragrant but not browned.
Cook the veggies: Add carrots and broccoli. Stir-fry 2 minutes.
Add bell pepper and snow peas. Cook another 2–3 minutes until crisp-tender.
Add noodles and sauce: Return noodles to the pan. Pour in sauce.
Toss with tongs for 1–2 minutes until the sauce thickens and coats everything.
Finish with shrimp and onions: Add shrimp and green onions. Toss 30–60 seconds to warm through. Drizzle with sesame oil.
Garnish and serve: Sprinkle sesame seeds if you like.
Taste and adjust with a splash of soy, vinegar, or a pinch of sugar. Serve hot.