In a large mixing bowl, combine flour, water, and egg. Mix until you have a smooth batter.
1 cup all-purpose flour, 1 cup water, 1 egg
Add the shredded cabbage, pork belly, green onions, tenkasu, and pickled ginger to the batter. Stir until all ingredients are well combined.
2 cups cabbage, 4 slices pork belly, 2 green onions, 1/4 cup tenkasu, 1/4 cup ginger
Heat a frying pan or griddle over medium heat and lightly oil it.
Pour a portion of the batter onto the pan, shaping it into a round pancake. Cook for about 4-5 minutes on each side, or until golden brown and cooked through.
Repeat with the remaining batter.
Serve the okonomiyaki hot, drizzled with okonomiyaki sauce and Japanese mayonnaise. Sprinkle bonito flakes and aonori on top.
1/2 cup okonomiyaki sauce, 1/4 cup mayonnaise, 1/4 cup bonito flakes, Aonori
Notes
You can add other ingredients like shrimp or cheese to the batter for variation.
If you can't find okonomiyaki sauce, you can make a quick substitute with Worcestershire sauce, ketchup, and soy sauce.