Cook the noodles in boiling water according to package directions, then drain and set aside.
In a small bowl, whisk together the hoisin sauce, soy sauce, and oyster sauce to create the base sauce.
Heat 15ml of vegetable oil in a wok or large skillet over high heat until shimmering.
Add the beef strips in a single layer and sear until browned, approximately 2-3 minutes. Remove beef from the pan and set aside.
Add the remaining vegetable oil to the wok, then add the garlic, ginger, bell pepper, and broccoli. Stir-fry for 3 minutes until vegetables are tender-crisp.
Return the beef to the wok along with the cooked noodles and the prepared sauce mixture.
Toss continuously for 2 minutes over high heat until the sauce has thickened and evenly coated all ingredients.
Remove from heat, drizzle with sesame oil, and garnish with sliced green onions before serving.