Prepare the vegetables: finely shred the Cabbage and thinly slice the Green Onions. Drain any excess liquid from the shredded cabbage so the batter won’t become soggy.
Grate the Nagaimo (or mash if needed) to create a slightly sticky binder, and beat together with the Eggs.
In a mixing bowl, whisk the All-Purpose Flour with the Dashi until smooth, then fold in the nagaimo-and-egg mixture to make a loose batter.
Fold the shredded cabbage, most of the sliced green onions, and the Tenkasu into the batter; add the Beni Shoga if you like a little pickled tang.
Heat a nonstick skillet or griddle over medium heat and add a little Neutral Oil. Spoon or pour a generous ladle of batter into the pan and shape into a round pancake about 6–8 inches wide.
Lay a few slices of Pork Belly over the top of the pancake and cook covered for 4–6 minutes, until the bottom is golden and the batter is mostly set.
Flip the okonomiyaki carefully (use two spatulas) so the pork side cooks down; press lightly and cook another 4–6 minutes until the pork is cooked through and both sides are nicely browned.
Transfer the pancake to a plate and brush the top with Okonomiyaki Sauce. Drizzle in a decorative pattern with Japanese Mayonnaise.
Finish by sprinkling Aonori and scattering Katsuobushi over the top — the bonito flakes will dance in the heat. Cut into wedges and serve immediately.
