Grind oatmeal into powder using a food processor.

In a bowl, beat the egg and mix with water and dashi powder. Add the ground oatmeal and let it sit for 10 minutes to form the batter.

Slice green onions into small pieces and mince pickled ginger.

Cut boiled octopus into 2cm cubes.

Heat a takoyaki pan and lightly grease with salad oil. Pour batter halfway into each mold, add octopus, green onion, and pickled ginger, then fill molds to the brim with batter.

Cook for 3–5 minutes until edges solidify. Push overflowed batter into the mold and rotate each piece halfway. Continue cooking until golden brown and fully cooked.