In a large mixing bowl, combine the all-purpose flour, baking powder, salt, eggs, and dashi broth. Whisk until you have a smooth batter.
Add the finely chopped cabbage and green onions to the batter. Mix everything together until well combined.
Heat a non-stick pan or griddle over medium heat. Grease it lightly with oil.
Pour half of the batter onto the hot pan and spread it out into a round shape, about ½ to ¾ inch thick. Repeat with the remaining batter.
Cook the Okonomiyaki for about 4-5 minutes one side, then cover and steam for 3 minutes. Flip and fry until golden brown on both sides and cooked through.
Once cooked, transfer the Okonomiyaki to a serving plate.
Drizzle Okonomi sauce and Japanese mayonnaise generously over the top. Sprinkle with katsuobushi, green onion, and aonori for that final touch of flavor and visual appeal.
Serve immediately while hot.
