Make the Yakisoba sauce by mixing the soy sauce, oyster sauce, Worcestershire sauce, and sugar. Set aside.
Saute the beef slices until they turn brownish. Set aside.
Open the pack of soba. Pour boiling water to the soba and lose them with a chopstick. Drain the soba and set them aside.
Take another wok and start stir-frying the mushrooms for about two minutes.
Add in other vegetables and keep stirring for another two minutes
Add in the sauteed beef, the noodles, and the Yakisoba sauce.
Continue the stir fry until they all mixed evenly and cooked thoroughly.
Yakisoba is ready to serve