01 - Combine beef slices with soy sauce, sesame oil, and cornstarch in a bowl. Let rest for 10 minutes to marinate.
02 - Cook noodles according to package directions. Drain and rinse under cold water, then set aside.
03 - In a small bowl, whisk together soy sauce, oyster sauce, hoisin sauce, rice vinegar, sriracha, brown sugar, and water until smooth.
04 - Heat 1 tablespoon vegetable oil in a large wok or skillet over high heat. Stir-fry marinated beef for 2 to 3 minutes until just cooked. Remove and reserve.
05 - Add remaining vegetable oil to the wok. Stir-fry bell peppers, carrot, and sugar snap peas for 2 to 3 minutes until crisp-tender.
06 - Incorporate garlic, ginger, and sliced chilies into the wok. Stir-fry for 1 minute until fragrant.
07 - Return beef to the wok. Add noodles and sauce, tossing everything together for 2 to 3 minutes until heated through and evenly coated.
08 - Sprinkle spring onions on top before serving.