See the full recipe for optional adds. Feel free to experiment, create, have fun, and enjoy. It's only dressing for one night, so how far wrong could you go? Note that guests have been known to tip up their bowls and drink the left over dressing.
Again, when I make it, I don't measure—it's the variety that makes it interesting from night to night
Nota Bene—This recipe originated in the days before washed boxed lettuce, when each leaf had to be washed (and checked for slugs, because mostly, the lettuce came out of our own garden). Even shaken dry, the lettuce still carried some water, which diluted the dressing somewhat. If you're using lettuce that doesn't get rinsed, you might want to cut in a tomato (which my aunt always did, for a refreshing change), or a cucumber, something that will add a bit of moisture.