Ask HN: What is the best tutorial you've ever worked through and why?

I'm currently working on writing a tutorial on saltstack. As I think through the problems of trying to help someone else build a mental model, I feel like I don't really know enough theory of how that is done. It occurs to me that I've never read a close reading or literary/pedagogical analysis of a tutorial. I am currently drawing most of my inspiration from things that I liked about the django and angularjs tutorials, but I really would like to broaden my horizon.

So I want to know: are there any good tutorials I should also check out? Anyone who has written an analysis of what makes a good tutorial?