i think the zen i was taught is closest to this teaching of the buddha from the Bahiya Sutta
"Then, Bahiya, you should train yourself thus: In reference to the seen, there will be only the seen. In reference to the heard, only the heard. In reference to the sensed, only the sensed. In reference to the cognized, only the cognized. That is how you should train yourself. When for you there will be only the seen in reference to the seen, only the heard in reference to the heard, only the sensed in reference to the sensed, only the cognized in reference to the cognized, then, Bahiya, there is no you in terms of that. When there is no you in terms of that, there is no you there. When there is no you there, you are neither here nor yonder nor between the two. This, just this, is the end of stress."
but like i said before zazen other than in the shikantaza style is just anapanasati, not vipassana.
This is a very interesting Sutta quote, thank you.
It is also how I understand shikantaza (choiceless awareness, silent illumination), although I never had instruction from a Soto teacher.
As for other Zen meditation, I agree with the earlier poster who said that although it resembles anapanasatti it is less structured and maybe somewhat different in spirit.
For example you may get an instruction to observe your breath, and return to it when you get distracted. But getting distracted is also a part of the process as is returning. So while you are making an effort to stay with it, the actual mechanics is far less important than discovering what your mind is like and developing this alert non-judgmental attention.
And then when the concentration is stabilised, one asks: who is paying attention? This is really the crux of zazen - not the concentration on this or that, but the turning around of this focused awareness back on itself. "Show me your mind, so I can pacify it!" Bodhidharma (the legendary founder of Zen) bellowed at Huiko.
This is considered the root of practice - insight into who I really am (or am not). And while there are moments of other sort of insight along the way, they are kind of incidental and not the focus of the practice itself, as I understand it.
Mind you I am not a teacher, and Zen is a diverse tradition so not everyone will agree.