For the Okonomiyaki Pancakes: Set out a large mixing bowl. Mix the warm water and dashi in the bowl to dissolve the dashi.
Then whisk in the eggs, flour, and baking powder. Once the batter is smooth, fold in the shredded cabbage, scallions, and breadcrumbs.
Preheat the oven to 200 degrees to use as a warmer while you cook the pancakes. Then set a cookie sheet in the oven.
Set a small nonstick skillet over medium heat. Add 1 teaspoon sesame oil to the skillet. Add one-fourth of the batter to the hot skillet. Then press into a round even layer, about ½ inch thick. Place a lid over the skillet to steam the pancake as it cooks. Cook covered for 5 minutes per side.
Move the cooked pancakes to the warm oven and repeat until all four pancakes are ready.
For the Okonomiyaki Sauce: Meanwhile, in a small bowl, mix the oyster sauce, ketchup, and Worcestershire sauce together. (If you have a squeeze bottle, you can shake them together in the bottle, to make it easier to drizzle over the pancakes later.)1
When ready to serve, drizzle Okonomiyaki sauce and Kewpie mayo over the pancakes. Top them with chopped scallions, Bonito flakes, furikake seasoning, and sushi ginger. Serve warm.
If desired, you can add thinly sliced shrimp or pork to the pancakes as you fry them. If you have more than one small skillet, you can cook several pancakes at the same time.Fun fact: The thin Bonito flakes will move and wave once they hit the hot pancakes!Okonomiyaki will keep well in a sealed container for up to 5 days in the refrigerator. Reheat briefly in a skillet or bake for 10-15 minutes in a 350 degree preheated oven. The Okonomiyaki sauce will keep well stored in the fridge for up to two weeks.