1. Make the dashi by dissolving the dashi powder in the hot water and set aside to cool completely.
2. In a large bowl, add the batter ingredients (including cooled dashi) and mix until well combined. Let it stand for 30mins in the fridge.
3. Take out the batter from the fridge and mix in the cabbage until well combined.
4. Heat a large non-stick skillet and add 2T oil. Add half of the cabbage mix (don’t press down) and spread it around into a large disc in the pan. Cover and cook on med-low heat until the bottom is golden (about 10mins). Add in more oil to the pan if necessary then flip the pancake over and cook the other side until golden (5-10mins). Slide onto a serving plate.
5. Drizzle the tonkatsu sauce on top of your okonomiyaki. Be generous and squeeze out the sauce in a tight zig zag motion. Now drizzle Kewpie mayo across the pancake, perpendicular to tonkatsu sauce. You will end up with a lattice of two sauces.
5. Garnish with red pickled ginger, bonito flakes and spring onions.
6. Repeat to make the next okonomoyaki.