Remove the shell and deveining the prawn Mix the egg, flour, water and mayonnaise in a small bowl to make a batter Coat each prawn into the batter then place into the panko crumbs and coat. Heat frying oil in a deep frying pan to 350°F. Fry prepared prawn till crispy and golden brown on both side and set aside. Slice the onion thinly. Lightly beat the eggs in a bowl and set aside. Pour Dashi stock in a shallow frying pan and bring it to boil over high heat. Add sliced onion and turn the heat down to medium. Add Mirin, Sugar and Soy sauce and cook it for a few minutes till the onion is cooked. Place the Ebikatsu (a.k.a. fried shrimp) in the saucepan with the sauce, and pour the eggs over them. Cook further for couple of minutes until the eggs are half cooked and slightly runny. Remove from heat and serve over two bowls of rice.