Prep the vegetables:

1. Slice the onion and red pepper and put them into a bowl.
2. Cut the woody stem off of the shiitakes and then slice thin. Add it to the bowl of vegetables.
3. Peel and trim the carrot and slice on an angle. Stack the slices and cut through them to yield matchsticks. Add the carrots to the veggie bowl.
4. Trim and cut two of the scallions into 2 inch pieces. Add it to a separate bowl with the cabbage.
5. Trim and thinly slice the remaining scallion for garnish. Set aside.

Make the sauce:

1. Combine the soy sauce, worcestershire sauce, mirin, and dashi powder and stir together until the dashi powder has dissolved. Set aside.

Make the Noodles:

1. Heat a medium pot with 6 cups of water and bring it to a boil. Add the noodles and let them defrost in the water before gently untangling them with tongs or chopsticks. They are already boiled so once the noodles are separate, drain them into a colander and set aside.
2. Heat a large 12 inch skillet over medium high heat. Add 2 Tablespoons of oil and the chicken. Let the chicken cook for 1 minute and then stir fry for another minute.
3. Add the onion, peppers, mushrooms, carrots, and the remaining 2 Tablespoons of oil. Raise the temperature to high and stir fry for 2-3 minutes. 
4. Lower the heat to medium high and add the drained noodles and the sauce. Continue to stir fry for another minute.
5. Add the cabbage and scallions and stir fry for another minute or two until the cabbage has wilted.
6. Add the sesame oil and stir it into the noodles.
7. Transfer to a plate and garnish with the shaved bonito flakes and the scallions.
8. Serve immediately.