In a large bowl, whisk together the flour, dashi, and eggs until smooth.
Add the shredded cabbage and chopped green onions to the batter.
If using, fold in any optional add-ins.
Heat a lightly oiled skillet or griddle over medium heat.
Pour a portion of the batter onto the pan and shape into a round pancake.
Place pork belly slices on top.
Cook for 4–5 minutes until the bottom is golden, then flip carefully.
Cook the other side for another 4–5 minutes until fully cooked.
Transfer to a plate and drizzle with okonomiyaki sauce and Japanese mayonnaise. Sprinkle with aonori and katsuobushi. Serve hot.
Enjoy your meal!