Make a simple yakisoba sauce by mixing ½ tbsp oyster sauce, ½ tbsp Japanese soy sauce (koikuchi shoyu), 1 tsp Worcestershire sauce, ½ tsp tomato ketchup, ¼ tsp sake, ¼ tsp sugar, 1 pinch ground black pepper and ½ tsp toasted sesame oil in a small bowl.
Heat a frying pan on medium-high and once hot, add 1 ½ tsp cooking oil. Add 1 portion ramen noodles and fry 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 all-purpose flour, 60 ml dashi stock, 1 pinch white sugar and 1 dash mirin in a small jug until smooth.
Briefly lift the pan off the heat and pour 3/4 of the mixture into the center of the pan. Spread it out thin using the back of a spoon, then place the pan down and sprinkle 1 tbsp bonito flakes (katsuobushi) over the wet batter.
Add 50 g green cabbage, 4 tbsp fried squid snack (ikaten) and 50 g bean sprouts one layer at a time, then drizzle the leftover batter over the top.
Place the 100 g thinly 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 Japanese soy sauce (koikuchi shoyu) 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 egg into a separate bowl with 1 pinch salt and whisk until the yolk and white are combined.
Use kitchen paper to wipe the pan clean, then add a drizzle of oil and spread it around using kitchen paper to remove any 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).
Generously coat with the homemade okonomi sauce, 1 tbsp finely chopped green onions and an 1 pasteurized egg yolk (optional). Enjoy!