Combine the sauce ingredients (3 tbsp Worcestershire sauce, 1 tbsp tomato ketchup, 1 tsp Japanese soy sauce (koikuchi shoyu), 1 tsp mirin, 1 tsp honey and ⅛ tsp dashi granules) in a saucepan and bring to a gentle simmer over medium heat. Mix continuously to prevent splattering - I recommend using a spatula to scrape the bottom of the pan and prevent burning.
Simmer the sauce for 3 minutes to thicken, then remove from the heat and set aside for later.
Grind 1 tbsp bonito flakes (katsuobushi) and 1 tbsp dried baby shrimp (hoshi ebi) using a mortar and pestle until they become a fine powder.
Crack 2 eggs into a mixing bowl and add 1 tbsp Japanese mayonnaise and 600 ml water. Whisk until combined and scoop the foamy bubbles from the top.
Add 170 g all-purpose flour, 1 tsp aonori (dried green seaweed powder), 1 tsp dashi granules, and the ground bonito flakes/dried shrimp powder. Whisk until no lumps of dry ingredients remain.
Cut 100 g boiled octopus into bitesize pieces.
Start heating your takoyaki pan over medium heat and fill each crevice ¼ of the way with cooking oil - this is the key to creating an extra crispy exterior like gintaco. (It also prevents sticking.)
While you wait, add 1 Japanese leek (naganegi), 3 tbsp red pickled ginger (benishoga) and 30 g tempura flakes (tenkasu) to a separate bowl and mix until evenly distributed. This mixture will streamline the cooking process.
Pour the batter into the preheated takoyaki pan until each well is halfway full. Add a piece of octopus to each well.
Pour more batter over the top until all of the wells are full and the area around the wells are fully covered, then sprinkle with the leek/pickles/tempura flake mixture.
When the batter starts to firm up, use a bamboo skewer to draw lines vertically and horizontally between the wells, dividing them into individual pieces.
Use the bamboo skewer to scrape around the edge of each well in a circular motion and turn each takoyaki halfway.
After a few minutes, roll each takoyaki again and tuck in any excess batter.
Once all of the takoyaki are round, add more oil and continue to turn them occasionally until crispy all over.
Remove the takoyaki and repeat these steps until all of the batter and ingredients are used. Brush generously with the sauce and top with aonori (dried green seaweed powder) and bonito flakes (katsuobushi). Japanese mayonnaise is optional. Enjoy!
Notes
If some takoyaki brown more quickly than others, try swapping their positions for more even cooking.Real takoyaki typically has a slightly gooey center. If this isn't your thing, you can lower the heat slightly and cook them for longer.