Start by making the batter. Mix the flour, baking powder, sugar and sea salt together.
Grate the potato and add it to the dough.
Pour in the broth and mix well. Refrigerate for at least 1 hour.
Meanwhile, make the sauce by mixing the sauce ingredients.
Meanwhile, chop the Chinese cabbage very finely. Make sure there is no moisture in the cabbage, as it will make the dough thinner.
Slice the shiitake.
After an hour, add the four eggs to the batter and whisk. Add the finely chopped cabbage and stir well.
Heat a frying pan over high heat with plenty of oil and butter. When hot, pour the batter into the pan and lower the heat slightly. Spread the shiitake slices on top. Cover and cook for five minutes.
After 5 minutes, check to see if the bottom is nicely browned. If so, flip the pancake. Is it difficult or not daring? Then slide it onto a plate, place a second plate on top, flip it and slide it back into the pan.
Bake the second side with the lid on the pan for 5 minutes, then finish baking for another 2 minutes without the lid.
Transfer the pancakes to a plate and spread a few tablespoons of the okonomiyaki sauce on top. Drizzle the mayonnaise on top in the characteristic way (see photo) and finish with the bonito flakes and scallions.