Cook the noodles according to the package instructions if they are not already cooked. Drain well and set them aside.
Slice the chicken breast into thin strips. Mince the garlic, slice the bell peppers, shred the cabbage, and chop the green onions.
Heat the vegetable oil in a large skillet or wok over medium-high heat.
Add the sliced chicken to the hot pan. Cook for 5–6 minutes, stirring occasionally, until the chicken is fully cooked and no longer pink.
Add the minced garlic and cook for about 30 seconds, stirring constantly until fragrant.
Add the sliced bell peppers and shredded cabbage. Stir-fry for 3–4 minutes until the vegetables are slightly tender but still crisp.
Add the cooked noodles to the pan and gently toss everything together.
Pour in the soy sauce and oyster sauce. Stir well so the chicken, vegetables, and noodles are evenly coated with the sauce.
Drizzle the sesame oil over the stir fry and sprinkle in the black pepper. Mix everything together and cook for another 1–2 minutes until heated through.