Divide the green onion into green and white parts. Thinly slice the green part and mince the white part. Squeeze out excess water from the pickled ginger and mince it.

Cut the boiled octopus into small bite-sized pieces.

Mix the minced white onion with the Negi Sauce ingredients in a bowl.

Combine the Takoyaki Batter ingredients in a bowl. Add the sliced green onion, minced pickled ginger, and tempura flakes, then mix well.

Heat salad oil in a rectangular pan over medium heat. Pour the batter into the pan. When the edges start to set, scatter the octopus pieces and quickly fold the batter in half. Cook each side for 3-4 minutes over low heat until fully cooked.