Cook noodles according to package directions. Drain and set aside.
In a small bowl, whisk together soy sauce, oyster sauce, sesame oil, cornstarch, and water for the sauce. Set aside.
Heat vegetable oil in a large skillet or wok over medium-high heat. Add steak and stir-fry until browned. Remove steak from skillet and set aside.
Add shrimp to the skillet and stir-fry until pink and cooked through. Remove shrimp from skillet and set aside.
Add broccoli, bell pepper, and onion to the skillet. Stir-fry until vegetables are tender-crisp.
Add minced garlic and ginger to the skillet and stir-fry for 30 seconds until fragrant.
Return the cooked steak and shrimp to the skillet. Pour the prepared sauce over the ingredients and stir until the sauce thickens and coats everything.
Add the cooked noodles to the skillet and toss to combine. Serve immediately.
Notes
Garnish with sesame seeds or chopped green onions if desired.