Add 0.75 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.