It's kind of funny for a gringa like me to say this is a favorite I grew up on, but it's true; my dad learned it from a Mexican friend way back, and it's been my favorite soup as long as I can remember. My dad always uses celery; I don't always have it around, it's fine to omit it. Feel free to adjust seasonings to taste. The tomatillos thicken this dish as well as adding flavor; I haven't seen them in any other recipe, but I consider them essential! Almost all measurements are approximate; I just judge by eye and throw stuff in! This soup is killer with homemade tortillas.