In a medium bowl, whisk together the flours, baking powder, eggs, and dashi.
Plug the takoyaki maker and turn it on. Brush the molds and the top surface lightly with sesame oil. In a small bowl mix together the octopus and the onions and set aside.
When the takoyaki maker is hot, pour a little batter into each mold until they are ¾ of the way full. Place a pinch of the octopus-onion mixture in the center of each mold, then add a little more batter to each one to cover the filling. (It’s okay if a little batter spills over.) Cook until the underside of the takoyaki balls are golden brown, 3–4 minutes. Using a skewer, carefully flip each ball over and continue cooking until the balls are uniformly golden brown and their insides are cooked but soft, 1–2 minutes more. Transfer to a plate and repeat until all the batter has been used.
Squirt the takoyaki sauce and mayonnaise over the balls, top with red ginger and bonito flakes, and serve immediately.
