In a small bowl, whisk together the cornstarch, soy sauce, and sesame oil. Place the sliced beef in a shallow bowl and pour the marinade over it. Marinate for 30 minutes, up to 8 hours.

Cook the noodles according to package instructions. Once cooked, transfer the noodles to a bowl filled with ice water and let them cool. Set the noodles aside.

(Have all of your ingredients prepped and ready to go. Cooking this dish goes quickly because of the high heat, and you won’t want to leave the wok unattended while you try to chop your ginger or garlic.)

Heat a large wok or skillet over medium high heat. Add 2 teaspoon of oil. Add the beef and sear until browned, 1-2 minutes, stirring just enough so it cooks on all sides. Remove the beef from the pan and place it in a bowl. Set the beef aside.

Add the remaining 2 teaspoon of oil to the wok if it looks dry. Then, add the garlic and ginger. Sauté for 10-15 seconds, until fragrant. Add the green onions and the cooked, drained noodles. Let this cook, undisturbed for 30 seconds. Add the soy sauce and rice wine vinegar. Scrape the stuck bits off of the bottom of the pan and sauté for 30 seconds, stirring until everything is coated with sauce and heated through. Finally, add the bean sprouts and return the beef to the pan. Sauté for 30 seconds more.