Make a simple yakisoba sauce by mixing ½ tbsp oyster sauce, ½ tbsp soy sauce, 1 tsp Worcestershire sauce, ½ tsp tomato ketchup, ¼ tbsp sake, ¼ tsp sugar, 1 pinch ground black pepper and ½ tsp sesame oil in a small bowl.
Heat a frying pan on medium-high and once hot, add 1 ½ tsp cooking oil. Fry the yakisoba noodles until slightly crispy.
Pour the yakisoba sauce over the noodles and stir fry until they're evenly coated. Remove from the stove and set aside for later.
Take a large frying pan and heat on medium-low. Add 1 ½ tsp cooking oil and wipe it around the pan with kitchen paper to remove the excess.
While the pan is heating up, make the crepe batter by whisking the 30 g cake flour, 60 ml dashi stock, 1 pinch white sugar and 1 dash mirin in a small jug until smooth.
Pour 3/4 of the mixture into the center of the pan and spread it out using the back of a spoon. Sprinkle 1 tbsp bonito flakes over the batter while it's still wet.
Add 50 g green cabbage, 4 tbsp fried squid snack (ikaten) and 50 g beansprouts one layer at a time, then drizzle the leftover batter over the top.
Place the 100 g thin sliced pork belly slices over the top and add a lid. Cook for 5 minutes.
While it's cooking, make the okonomi sauce by mixing the ½ tbsp Worcestershire sauce, ½ tbsp oyster sauce, 1 tbsp tomato ketchup, ½ tbsp honey and ½ tsp soy sauce in a small bowl. Set aside for the end.
Flip the okonomiyaki and cook on the other side for another 5 minutes, again with the lid. Once the pork is cooked through, transfer the contents of the pan to a large plate.
Crack 1 medium egg(s) into a separate bowl with a pinch of salt and whisk until the yolk and white have combined.
Use kitchen paper to wipe the pan clean, then add a drizzle of oil and spread it around using kitchen paper to remove the excess. Pour the whisked egg into the pan and swirl it around to evenly coat the bottom of the pan.
Once it's about 80% cooked, place the cooked yakisoba and the other half of the okonomiyaki on top so the crepe side is on top.
Use a spatula to peel the edges of the egg and loosen it from the pan and carefully flip the whole thing onto a plate (so the egg is on top). and
Generously coat with the homemade okonomi sauce, 1 tbsp finely chopped green onions and an 1 pasteurized egg yolk (optional).