1. In a medium bowl, add flour, sugar, a dash of salt, baking powder and baking soda, mix well with a cooking whisk.
2. In a separate bowl, add beaten egg, milk, water, soy sauce and mirin, and then mix well.
3. Pour the egg mixture to the flour mixture little by little and stir until well mixed using a cooking whisk.
4. Grease a taiyaki pan lightly with vegetable oil and pre-warm over a medium heat. Pour the taiyaki batter thinly on the pan. Put the filling which you want in the center of each taiyaki and spoon some more batter on top to cover the filling.
5. Close the lid and flip the taiyaki pan to cook the other side of taiyaki. Cook for about 1 to 2 minutes or until both side are golden brown, open and check the progress. If the taiyaki is not golden brown, cook a bit longer until it is golden brown evenly.
Note : If you want to use Japanese curry paste (about 200 g), prepare it first as follows : in a small pan, add curry paste and sifted flour (15g) and mix well. Then heat up over medium heat until it becomes thick.