In a mixing bowl, whisk together the flour, eggs, dashi stock, soy sauce, and salt until smooth. The batter should be thin and pourable.
Heat the takoyaki pan over medium heat and grease each mold generously with oil to prevent sticking.
Pour the batter into the molds, filling them to the brim. Add a piece of octopus, a sprinkle of green onions, tempura scraps, and pickled ginger into each mold.
Allow the batter to cook for 1-2 minutes. Use skewers or chopsticks to gently rotate each ball halfway, allowing the uncooked batter to flow into the mold and form a round shape.
Continue turning the takoyaki every minute to ensure even cooking. Cook for about 7-10 minutes, or until the takoyaki are golden brown and crispy on the outside.
Transfer the takoyaki to a plate and drizzle with takoyaki sauce and Japanese mayonnaise. Sprinkle with bonito flakes and seaweed powder for a finishing touch.
Serve hot and enjoy!