Bring 2 quarts of water to boil in a 3 quart saucepan over high heat. Add noodles, return to a rolling boil and cook to package directions until al dente. Drain in a colander and rinse several times with cold water, shaking to remove excess water. Return noodles to unwashed pan, add sesame oil and toss until well combined.
Combine chicken, 1 tsp sherry, 1 tsp soy sauce, salt and pepper in a shallow bowl.
Combine remaining 1 tbl sherry and soy sauce in a small bowl. Heat wok (frying pan) over high heat until a bead of water vaporizes within 1 to 2 seconds of contact. Swirl in 1 Tbl oil and add pepper flakes. Stir fry 10 seconds or until red pepper flakes are fragrant. Push flakes to side of pan, add chicken mixture and spread evenly. Cook undisturbed 1 minute, letting chicken sear. Stir fry 30 seconds more or until chicken browns. Add cabbage and mushrooms and stir fry 1 minute or until cabbage is wilted. Transfer chicken and vegetables to a plate. Swirl remaining 1 Tbl oil into wok. Add noodles and stir fry 15 seconds. Swirl soy sauce-sherry mixture into wok and add scallions and chicken mixture. Sprinkle with remaining 3/4 tsp salt. Stir-fry 1-2 more minutes or until chicken is cooked through and noodles are heated through.