Cook the noodles according to package instructions.
Marinate the steak in cornstarch, soy sauce, and a bit of vegetable oil.
Heat a wok or a large pan over medium-high heat and add vegetable oil.
Add the marinated steak to the pan and stir-fry until browned, about 2-3 minutes.
Add the shrimp to the pan and cook until they turn pink, about 2 minutes.
Stir in the garlic and ginger, cooking for another minute.
Toss in the mixed vegetables and stir-fry for another 2-3 minutes.
Add the cooked noodles to the pan, followed by soy sauce and oyster sauce.
Garnish with sliced green onions before serving.