How to Make It
In a large bowl, whisk the flour, cornstarch, water, fish stock, egg yolk and salt until smooth. Stir in the seafood, scallions and onion. Cover and refrigerate for 15 minutes.
Combine all of the ingredients except the canola oil in a bowl.
In a 10-inch cast-iron skillet, heat 1/4 cup of the oil. Add one-fourth of the batter and spread in an even layer. Cook over moderate heat until deep golden on the bottom, 8 minutes. Flip the pancake, drizzle 1 tablespoon of oil around the edge and cook over moderately low heat until crisp, 8 to 10 minutes. Repeat with the remaining oil and batter. Serve hot, with the dipping sauce.