Ember 2.x How to do linked dropdowns with data sourced from server

I can't seem to find my first foothold on this. I found some older 1.x ways of kinda of doing what I want, but always from hard coded arrays.

Simply stated, I want a States drop down which gets its data from my server. When the user selects the state I need the Counties drop down to fetch the list of counties in that state from my server.

Pretty easy with straight Ajax and JS but learning the Ember 2.x way of doing it has proven elusive.

Are there any git projects, jsbins, twiddles or such that demonstrate the techniques needed to do this? Or someone adventurous enough to do a tutorial on it?