01 - Combine flank steak with 1 tablespoon soy sauce, 1 teaspoon cornstarch, and 1 teaspoon sesame oil. Mix thoroughly and let marinate for 10 minutes.
02 - Whisk together all sauce ingredients until smooth and set aside.
03 - Prepare lo mein or egg noodles according to package directions; drain, rinse under cold water, and set aside.
04 - Heat 1 tablespoon vegetable oil in a large wok or skillet over high heat. Add the marinated beef and stir-fry for 2 to 3 minutes until just cooked. Remove and set aside.
05 - Add the remaining tablespoon of vegetable oil to the wok. Stir-fry garlic, ginger, and onion for 1 minute until fragrant.
06 - Add broccoli florets and julienned carrot, stir-frying for 2 to 3 minutes until tender-crisp.
07 - Return beef to the wok, add the cooked noodles, then pour in the sauce. Toss and stir-fry for 2 to 3 minutes until heated through and well combined.
08 - Drizzle with extra sesame oil, garnish with sliced green onions and toasted sesame seeds. Serve immediately.