Will there be a pi.fyi fight over the superior regional Khao Soi? Who is to say. This is more or less the version I grew up with.
I am very liberal with the fish sauce, I sub the onion for shallot, I omit the gram flour and the crispy noodles. If I have time I make a fresh wheat noodle—if you have an extruder, fresh bucatini is obscenely good with this soup.
This dish is very rich so I like it with a little handful of arugula on top in addition to the egg, cilantro, shallot, and lime.