Cut the mini napa cabbage into bite-sized pieces.
Slice the onion and carrot into thin strips.
In a bowl, mix flour, water, and eggs to make the batter.
Add the chopped vegetables to the batter and mix well.
Add cooking oil to a heated pan.
Place a portion of the mixture on the pan and cook until golden brown on both sides.
Top with okonomiyaki sauce, mayonnaise, bonito flakes, and green onions to finish.