Cut the cabbage, carrot, onion, and mushrooms into bite sizes.
Heat oil in a large pan. Add cabbage, carrot, onion, and mushrooms in the pan and saute in high heat. Add yakisoba noodles in the pan and stir-fry 1 minute.
Put 1/3 cup of water in the pan and cover it with a lid. Steam the noodles for a few minutes. Take the lid off and add yakisoba seasoning or sauce.
Stir the noodles well and fry them for a few minutes.
Sprinkle ao-nori and beni-shoga over yakisoba before serving.