01 - Combine sliced beef with 1 tbsp soy sauce, cornstarch, and 1 tsp sesame oil in a bowl. Mix thoroughly and let rest for 10 minutes.
02 - Prepare noodles according to package directions. Drain, rinse under cold water, and set aside.
03 - Whisk together soy sauce, oyster sauce, chili garlic sauce, rice vinegar, brown sugar, and toasted sesame oil in a small bowl until smooth.
04 - Heat 1 tbsp oil in a large wok or skillet over high heat. Stir-fry marinated beef in batches for about 2 minutes until browned but not fully cooked. Remove beef and set aside.
05 - Add additional oil if needed to the wok. Stir-fry garlic and ginger for 30 seconds until fragrant. Add bell pepper, carrot, and sugar snap peas, cooking for 2 to 3 minutes until tender-crisp.
06 - Return beef to the wok along with cooked noodles. Pour sauce over all and toss to combine, heating through for approximately 2 minutes.
07 - Stir in sliced spring onions. Serve immediately, garnished with sesame seeds, fresh cilantro, and additional spring onions.