Marinate the Beef: In a bowl, mix minced garlic, sesame oil, soy sauce, oyster sauce, vinegar, and water with cornstarch. Toss the thinly sliced beef in this mixture and let it sit for 10 minutes to soak up those wonderful flavors.

Make Black Pepper Sauce: Combine dark soy sauce, oyster sauce, black pepper, water, and potato starch in a separate bowl. Mix thoroughly so the sauce has a nice, smooth consistency ready for your noodles.

Cook Udon Noodles: Bring water to a boil and cook the udon noodles for 1-2 minutes until slightly loose and tender. Drain and set them aside, ensuring they retain their chewy texture.

Cook Beef: Heat a generous drizzle of oil in a wok, then stir-fry the marinated beef until it’s beautifully browned (around 2-3 minutes). Once cooked, remove the beef from the pan and set it aside.

Combine Flavors: In the same pan, sauté minced garlic and sliced onion until fragrant and golden. Add the cooked udon noodles, beef, and prepared black pepper sauce. Gently toss everything with chopped Chinese cabbage until evenly combined and everything is heated through.