Slice the octopus (or other protein, if substituting) into bite-size pieces then pop aside.
100-140 g octopus pieces
Combine the plain flour and cornstarch in a bowl. In a separate bowl, whisk the egg. Add the egg to the dry mixture, then slowly pour in the dashi stock or water and whisk it all together. You're aiming for a thin, runny consistency here, so if it's too thick just add more water or dashi.
140 g plain flour / all purpose flour, 10 g cornstarch / cornflour, 1 egg, 450 ml dashi stock
Now, heat the takoyaki pan over a medium high heat and brush oil over the entire surface. Pour the batter into the centre of the pan and keep pouring until all the wells are full and the batter covers the entire plate.
Place one piece of octopus or chicken into each well, then scatter the spring onion, ginger and tempura crumbs across the lot. When the bottom of the batter starts turning crispy, use a chopstick to cut out a square shape around each takoyaki well.
100-140 g octopus pieces, 1/2 cup spring onion / green onion, 1-2 tbsp pickled ginger, 1/2 cup tenkasu
Next comes Masa's fancy technique. Move your chopstick in an 'L' shape around the each well, then immediately push down into the well to flip the batter, forming a rough ball shape as you go. It might take a few tries, but keep going and you'll quickly get the hang of it.
Continue flipping each ball occasionally as the batter becomes crispy and golden brown on all sides. The easiest way to do this is to pierce the takoyaki ball with the chopstick and pull upwards to flip.