Combine the ketchup, oyster sauce, maple syrup, Worcestershire sauce, and white pepper in a small bowl. Taste and adjust to your liking if needed.
In a large bowl, whisk eggs, water, and salt. Add flour and mix to incorporate.
Now add the vegetables and nori to the batter and use a spatula to mix in.
Heat 1 tablespoon of oil in your pan on medium-low heat. Pour half of the batter into the pan. Press it down to flatten it out. Shape it into a perfect circle.
Cook for 8-10 minutes on one side or until golden brown. Flip using two spatulas and cook for another 6-8 minutes. Repeat with the second half of the batter.
Serve the okonomiyaki hot or warm with okonomiyaki sauce (see above) and toppings of choice. Enjoy!