Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
                        -----sushi-----
   6      med.          -- raw, unshelled,
                        -- shrimp
                        -----marinade-----
   3      tablespoons   rice vinegar
   1      teaspoon      sugar
   1      pinch         msg
   4      tablespoons   water
     1/4  teaspoon      salt
                        -----filling-----
   4                    egg yolks
     1/4  teaspoon      salt
   1      pinch         msg
   1 1/4  teaspoons     sugar
   2 1/2  teaspoons     lemon juice

Preparation:

TO COOK PRAWNS: Leaving the shells of the prawns intact, insert the toothpicks along the inside curves to prevent curling. Drop the prawn into 3/4 pt of boiling water and cook briskly, uncovered, for about 3 minutes until pink and firm. Drain in a sieve and cool quickly under cold running water. Remove the toothpicks and peel the prawns, leaving the last section of shell and tail on each one. De-vein the prawns by making a shallow incision across their tops with a small, sharp knife. Lift out the vein. Butterfly the prawns by cutting along their inner curves 3/4 of the way through, spreading the open and flattening with a cleaver. MARINADE Put the vinegar, water, salt, sugar and MSG into a mixing bowl and stir together thoroughly. Add the prawns, marinade at room temperature for 1 hour. FILLING Drop the egg yolks into a small saucepan and beat lightly with a fork. Remove 2 1/2 t of the yolks and set aside. Add 3/4 pt of water to the remaining yolks, stir thoroughly, and cook over a moderate heat for 10-15 minutes until the yolks are firm and hard-boiled. Drain them in a sieve, and mash them into a paste. Beat the sugar, salt, salt, lemon juice, MSG, and the rest of the raw egg yolks and continue to beat. Rub the mixture through a fine sieve. TO ASSEMBLE AND SERVE Divide the seasoned egg filling into 6 equal parts and pack each part into the center of a prawn. Seal the edges by pressing them together. Serve at room temperature.