Here's one from Jim Lee's Chinese Cook Book (My favorite). He says that the secret of good soup is good soup stock. To keep the egg flakes afloat, the soup must be thickened with cornstarch first before the beaten eggs are stirred in.

Bring soup stock to a boil. Slowly pour in the cornstarch mixture while stirring the stock, until the stock thickens. Reduce heat so stock just simmers. Pour in the eggs slowly while stirring the soup. As soon as the last bit of egg is in, shut off heat at once. Serve with chopped scallions on top.

Substitutions And Variations: Tomato Egg-Drop Soup is just a variation of plain egg-drop soup. The added tartness of tomatoes gives this soup an extra "zing" and helps to pick up sagging appetites. The addition of 1 medium-size can of stewed tomatoes is all that is needed. Bring stock to a boil. Add the tomatoes. (Mash the tomatoes if the pieces are too large.) When soup boils again, add the cornstarch mixture as before. Add the eggs while stirring. Shut off heat at once and serve topped with the chopped scallions.