In a medium bowl, whisk together Worcestershire sauce, soy sauce, ketchup, oyster sauce, and sugar until well combined. Set the sauce aside.

If using instant yakisoba noodles, soak them in warm water for about 1-2 minutes until soft. Drain and toss with a bit of vegetable oil.

Preheat a large skillet or wok over medium-high heat until faint wisps of smoke rise.

Add 1 tablespoon of vegetable oil to the hot skillet, followed by sliced onion and julienned carrots. Stir-fry for 2-3 minutes until translucent.

Introduce shredded green cabbage into the skillet, stirring together. Stir-fry for another 2-3 minutes until wilted yet crunchy.

Toss the soaked yakisoba noodles and prepared sauce into the skillet. Stir-fry for 2-4 minutes, ensuring noodles are well-coated.

Stir in most of the sliced green onions, reserving a small amount for garnish. Toss for about 1 minute.

Transfer yakisoba to bowls, garnishing with reserved green onions. Optionally, sprinkle sesame seeds or serve with pickled ginger.