Cut the steak across the grain into 1/4 inch by 2 inch slices.
Prepare the sauce by combining the plum sauce, soy sauce, rice vinegar, sesame oil, garlic, and ginger.
Pour 1/4 cup of the sauce in a measuring cup with the cornstarch and mix well.
Pour the remaining sauce over the meat and marinate in the refrigerator for at least 30 minutes.
Prepare the noodles according to the package directions.
Remove the beef from the marinade and discard the marinade.
Heat the vegetable oil in a large skillet over medium high heat. Add the beef and cook for 2-3 minutes. Remove the beef from the pan.
Add the carrot, pepper, peas, and green onions to the pan and stir fry for 4-5 minutes.
Stir in the reserved sauce, tossing to coat the vegetables.
Return the beef to the pan and add the noodles. Toss to combine and cook for 1 minute to heat through.