The vinegar in the water is to keep the shell from splitting open while boiling, the key to easy shelling is the ice water bath, the faster you cool the shell down cold, it will shrink the egg away from the shell so the membrane doesn't stick. (as my gma told me years ago) the other thing is to take the egg and tap tap tap it all around the egg on the counter, kinda like many spider web breaks like a car windshield after a crash, broken, intact, but flexible, you can roll the egg around with the palm of your hand on the counter top, to mush the shell and make sure you cracked all of it, some times I can peel the whole shell off in one piece that way and hardly anything sticks, this is old farmlore kiddo...another thing, the eggs stay better left in the shell (hardboiled that is in the refrig) if you aren't using them right away,, then you can crack them and peel them as needed. A good way to preseve eggs longer. Good luck, it takes a little practice.