Prepare the ingredients: loosen the Yakisoba Noodles if packaged (run under warm water or briefly microwave to separate), thinly slice the Pork Belly, core and roughly chop the Cabbage, slice the Onion into wedges, julienne the Carrot, and rinse the Bean Sprouts.
Make the sauce in a small bowl by whisking together the Japanese Worcestershire Sauce, Oyster Sauce, Ketchup, Soy Sauce and Sugar until smooth; taste and adjust balance of sweet/tangy as you like, adding a pinch of Salt and Black Pepper if needed.
Heat a large skillet or wok over medium-high heat and add the Neutral Oil. When shimmering, add the sliced Pork Belly and stir-fry until it starts to brown and render fat, about 3–4 minutes.
Push the pork to one side of the pan, add a little more Neutral Oil if the pan is dry, then add the Onion and Carrot. Stir-fry until they begin to soften, about 2–3 minutes.
Stir everything together and add the chopped Cabbage. Cook until the cabbage wilts but still has some bite, another 2 minutes, then add the Bean Sprouts and toss briefly—you want them just tender-crisp.
Add the loosened Yakisoba Noodles to the pan, breaking them apart if needed. Pour the prepared sauce evenly over the noodles and vegetables, then toss and stir-fry on high until the noodles are evenly coated and heated through, 1–2 minutes. Season to taste with extra Salt and Black Pepper if desired.
Turn off the heat and plate the yakisoba. Garnish generously with Beni Shoga, sprinkle with Aonori and finish with a scattering of Katsuobushi before serving for an authentic, aromatic finish.
