01 - Combine chicken pieces with soy sauce, sake (if using), and grated ginger in a bowl. Let marinate for 10 minutes to infuse flavors.
02 - Whisk together flour, baking powder, and salt in a large bowl until evenly combined.
03 - Beat eggs in a separate bowl, then add dashi stock (or water) and mayonnaise. Mix until smooth and well incorporated.
04 - Pour wet mixture into dry ingredients and stir until just combined. Avoid overmixing; small lumps are acceptable for proper texture.
05 - Fold shredded cabbage, spring onions, and grated carrot into batter until evenly distributed throughout.
06 - Heat large non-stick skillet or griddle over medium heat and add small amount of oil to prevent sticking.
07 - Add marinated chicken pieces to pan and cook for 2-3 minutes until lightly browned but not fully cooked through.
08 - Shape about one-quarter of batter into round pancake approximately 3/4 inch thick in pan, pressing chicken pieces evenly into each pancake.
09 - Cook for 4-5 minutes per side, pressing gently with spatula, until golden brown and cooked through completely. Repeat with remaining batter and chicken.
10 - Transfer to serving plates. Drizzle generously with okonomiyaki sauce and Japanese mayonnaise. Sprinkle with aonori and katsuobushi, and add pickled ginger if desired. Serve immediately while hot.