Prepare the Yakisoba Sauce: In a small bowl, whisk together the soy sauce (4 tbsp / 60ml), oyster sauce (3 tbsp / 45ml), Worcestershire sauce (2 tbsp / 30ml), ketchup (2 tbsp / 30ml), sugar (1 tbsp / 15g), grated garlic (1 tsp / 5g), and grated ginger (1 tsp / 5g). Mix until the sugar is fully dissolved. Set aside.

Prepare the Noodles: If using fresh or frozen yakisoba noodles, gently separate them. If they are very stiff, you can briefly microwave them for 30 seconds (about 2000W) or blanch them in hot (not boiling) water for 1-2 minutes to make them more pliable. Drain them thoroughly. If using dried noodles, cook them according to package instructions, drain well, and set aside. Be careful not to overcook them at this stage.

Cook the Pork: Heat 1 tbsp (15ml) of vegetable oil in a large wok or a spacious skillet over medium-high heat. Add the thinly sliced pork belly or loin. Stir-fry for 3-5 minutes, or until the pork is cooked through and lightly browned. If using pork belly, render out some of the fat. Remove the cooked pork from the wok and set aside, leaving any rendered fat in the wok.

Stir-fry the Vegetables: Add the remaining 1 tbsp (15ml) of vegetable oil to the wok if needed. Add the sliced yellow onion and julienned carrots. Stir-fry for 2-3 minutes until the onions are slightly softened and translucent, and the carrots begin to soften. Add the shredded cabbage and julienned green bell pepper. Continue to stir-fry for another 3-4 minutes until the vegetables are tender-crisp. You want them cooked but still retaining a slight bite.

Add Noodles and Pork: Push the vegetables to one side of the wok. Add the separated yakisoba noodles to the empty side. Pour about half of the prepared Yakisoba sauce over the noodles. Stir-fry the noodles for 1-2 minutes, separating them further and coating them with the sauce. Then, add the cooked pork back into the wok with the noodles and vegetables. Toss everything together to combine.

Incorporate Remaining Sauce and Bean Sprouts: Pour the remaining Yakisoba sauce over the entire mixture in the wok. Toss everything vigorously for another 2-3 minutes, ensuring all ingredients are evenly coated with the sauce and heated through. If using, add the bean sprouts during the last minute of cooking and toss gently just until they are slightly wilted but still crisp.

Serve: Divide the hot yakisoba noodles among four serving plates or bowls. Garnish generously with katsuobushi (bonito flakes), aonori (seaweed flakes), and pickled red ginger (beni shoga), if using. Serve immediately.