Marinate the sliced steak with 2 teaspoons of soy sauce, a pinch of salt, and a pinch of ground black pepper.
Boil noodles according to package instructions. Once done, drain and rinse under cold water. Mix in a little bit of oil to prevent them from sticking, then set aside.
While the noodles are cooking, add all the sauce ingredients to a bowl and mix well.
Heat 1 tablespoon of oil in a large non-stick pan or skillet over medium to high heat. Add sliced bell peppers and onions to the pan. Sauté for about 5 minutes until they become soft. Add 1/4 tsp salt and 1/2 tsp black pepper, mix well.
Remove cooked bell pepper and onions from the pan and set aside.
Add 1 tablespoon of oil and sliced steak to the pan. Sauté for 1 minute.
Add chopped garlic, the white parts of the green onion, and grated ginger to the pan. Cook for 30 seconds to release the fragrance.
Add sliced mushroom and stir-fry for a couple of minutes until the mushrooms start to become soft. Reduce the heat to medium, then return the cooked bell peppers and onions to the pan.
Add the cooked noodles to the pan and pour the prepared sauce all over the noodles. Mix until everything is evenly coated in the sauce. Remove from heat.
Plate the noodles and garnish with some roasted sesame seeds and the rest of the green onions, if desired. Enjoy!