Make the batter by mixing all the ingredients together.
Heat the takoyaki pan on the stove over medium-low to medium heat. Brush or spray the holes generously with oil.
When the oil starts to smoke, pour batter into the holes to fill them halfway through.
Sprinkle the chopped chicken teriyaki, carrot and cabbage on top of the batter.
Pour in more batter to cover the filling and the holes.
Cook the takoyaki for about a minute until the undersides start to set. Using skewers or chopsticks, gather the excess batter around each hole and lightly folding it on top of the ball as you invert. Cook for another minute or so until the batter is cooked through and the surface of the balls are lightly browned.
Repeat until you have used up all the batter and fillings.
Arrange the takoyaki on a plate. Drizzle mayo-Sriracha and thickened teriyaki sauce over them. Garnish with bonito flakes and scallions.