1. Whisk the flour, baking powder, and salt together in a large mixing bowl. In a separate container, lightly whisk the two eggs and the water or dashi stock until combined.

2. Pour the wet egg mixture into the dry ingredients and stir gently until just combined. Fold in the finely shredded cabbage, chopped scallions, and diced shrimp. Use a spatula to gently mix until the vegetables are coated, being careful not to overmix.

3. Heat a large frying pan or griddle over medium heat and add one tablespoon of a neutral cooking oil.

4. Scoop one-quarter of the mixture into the hot pan, forming a pancake about six inches wide and one inch thick. Cook for five to six minutes, or until the edges are firm and the underside has formed a deep golden, crispy crust.

5. Carefully slide a wide, sturdy spatula underneath the pancake. In a swift, confident motion, lift and flip the pancake over. Add a small amount of extra oil if the pan is dry, and gently press the pancake to ensure even contact with the heat.

6. Cook on the second side for another five to six minutes until thoroughly cooked through. Transfer the cooked pancake to a serving plate and immediately smother it with Okonomiyaki sauce and a generous zigzag of Japanese mayonnaise. Finish with a sprinkle of Aonori and Katsuobushi. Serve immediately.