Mince the onion finely. Divide the shrimp into two portions: mince half finely and chop the other half coarsely.

In a bowl, crumble the fish cake into small pieces using your hands.

Add shrimp, onion, potato starch, mayonnaise, and salt and pepper to the bowl. Mix thoroughly until combined. Divide into 4 portions and shape each into an oval patty.

In a separate bowl, beat the egg and mix with flour and water to create a batter.

Dip each patty into the batter, then coat thoroughly with breadcrumbs.