In a large bowl whisk together the dry ingredients: All-Purpose Flour, Baking Powder, Sugar and Salt until evenly combined.
In a separate bowl beat the Egg with the Milk and about 1–2 tablespoons of Neutral Oil until smooth.
Pour the wet mixture into the dry ingredients and stir until you have a smooth, lump-free batter. Let the batter rest for 10–15 minutes to hydrate.
Heat a bungeoppang or taiyaki pan over medium heat and lightly brush each mold with a little more oil to prevent sticking.
Spoon a thin layer of batter into each mold (enough to cover the bottom), then add about 1 teaspoon (or to taste) of Sweetened Red Bean Paste in the center of each, and cover with more batter so the filling is sealed.
Close the pan and cook for 2–4 minutes, then flip the pan and cook another 2–4 minutes more, or until the fish-shaped cakes are puffed and golden brown on both sides.
Remove the bungeoppang from the pan and cool on a rack for a minute or two so the filling sets slightly—serve warm for the best texture and flavor.
