I just do this; which turns into a "not doing" of course once you actually do it.
If you notice the attention going to whatever thought or feeling: drop it.
This way whatever object appears in the field of awareness I just know it's not me and attention "dies off" so to speak. What remains you can't even say what that is until after the practice; and you could call it "darkness" or "void" for the absence of any single thing. I'm not sure this is self inquiry but it's working out for me...