There once was a recipe, and if I had to take a wild guess I'd say it probably came from the Joyce Chen Cook Book, but my egg drop soup evolved over many years of trial and error. Which is not to say it's complicated, and it sounds like you already know the fundamentals. You can use your broth of choice; because I so often eat with vegetarians, I've taken to using vegetable bouillon, prepared a bit more thinly than directed, rather than the more traditional animal-based broth or stock.
Boil your broth of choice and add to it:
- A generous thumb-sized piece of ginger, finely chopped*
- Several shakes of fire oil
(can substitute crushed red pepper flakes)
- Soy sauce to taste (unless your broth or bouillon is already very salty)
In a measuring cup or small bowl, mix a bit of corn starch and water. I usually prepare about 1/4 cup of corn starch when making one to two quarts of soup. The water is to keep the corn starch from cooking in lumps when you add it to the boiling broth; you just need enough so that you can easily pour the mixture in a bit at a time. The corn starch is a thickener which affects the way the egg cooks. If your broth is very thin, your egg will tend to cook in wispy strands or large chunks. A slightly thicker broth enhances the delicate ribbon shape which should be your goal. I don't really know how to explain how to tell when your broth is thick enough except to use trial and error, and in my opinion it's better to be too thin than too thick (my wife prefers it thicker, so this is a matter of taste).
Beat your eggs (1-2 large eggs per pint of broth, as you like) and add a splash of Chinese rice wine if you've got it, dry sherry if you haven't. Don't use sake unless you can find a particularly dry variety, definitely don't use mirin (which is too sweet) or rice wine vinegar (which is vinegar
, for crap's sake, not wine!), and be sparing with it. I'd say a tablespoon per two large eggs is about right.
Remove the broth from the heat and give it a good, steady stir in one direction with a wooden spoon or a ladle. While stirring, slowly pour the beaten egg into the broth. Provided you do this right after taking it off the boil (a heavy-bottomed pan helps by retaining heat), the egg will cook almost immediately and you can just let it sit for a minute before garnishing with chopped scallions and serving. Pouring the egg through the tines of a fork, held at a certain height above the broth, can help control the shape and thickness of the egg when it hits the broth; but if you're using two hands for the egg and fork, you can't stir, and stirring helps to keep the egg from clumping. If you ask some people, making the egg bits just the right shape and consistency is 99% of making a good egg drop soup, but I think as long as you've got the taste right the eggs don't have to be perfect. As long as you avoid the two pitfalls which are large clumps of scrambled eggs from pouring too fast or wispy, mushy strands from broth that has cooled down so it's not cooking the eggs before they can fall apart.
*Rule of thumb: If your thumb might be smaller than my thumb, add two thumbs of ginger instead of one. Universal truth: There is never any such thing as too much ginger.