Hanan method. Very basically, it's based on getting your child to communicate by commenting on what they are focussing on/are interested in, rather than what you want them to do. So, if your child is banging two blocks together, you get down to their level and say, "Bang the blocks," or something like that. What I used to do was say, "Look at the car, DS, brum, brum," while he continued to ignore me and play with the blocks.
You give them the words for what they are interested in, what they are looking at, rather than trying to get them to do something else. You don't just leave it there, you expand on what they are doing, giving them more words. You take some blocks, red and blue and you bang them, copying what they are doing, and give them the colour names, etc. When I copied what my DS was doing I always seemed to get his attention.
It's not very ABA, but it did work very well with my DS. There is an (expensive) book called More than Words which is aimed at DC on the spectrum which goes into more detail. This book takes you through your child's sensory needs and helps you to understand what makes them tick.
There is also the standard book, not ASD specific, called It Takes Two to Talk. Either can be purchased through the Winslow Press.
My DS2 did turn out to be HF, with an average to high IQ. Whether this approach is the best one for all children, I wouldn't know, probably not. It just resonated with me and worked really well with my DS.