- Fill enough water to cover egg in a small sauce pan and bring it to a boil. Place egg in and let it simmer under medium heat for 9 mins. Let boiled egg sit for 10 mins, remove from saucepan and remove shell and let it cool.
- Mash egg into fine crumbs. Add in all the tartar sauce ingredients and mix well. Set aside.
- Heat up frying pan with oil and sauté onion until soften. Remove and set aside to cool.
- Smash prawns with knife and give them a rough chop.
- Place chopped prawns with sautéed onion, potato flour, salt, pepper and wasabi in a mixing bowl and mix them all until well incorporated.
- Divide into 2 equal portions and flatten them into square patties.
- Set up coating station of flour, beaten egg and panko. Coat prawn patties with flour then beaten egg follow by panko.
- Heat up oil in a frying pan to 180°C and fry prawn patties one at a time until both sides turn golden brown. Drain oil and let them cool on cooling rack.
- Alternatively, bake coated prawn patties sprayed with some oil in the oven at 180°C for 25 mins or 15 mins in the air fryer. Turn them over mid way.
- Place one prawn patty on a slice of bread, top with shredded cabbage and tartar sauce and cover with another slice of bread.