lots of old school bakeries in queens still make them and so do some of the grocery stores. ithink I have gotten them at stop and shop in maspbeth
also tomcat bakery makes a pull apart parkerhouse roll with carmelized almost burnt onions on top and poppy seeds that is a definite takeoff on the old school onion rolls but much better quality. they only sell wholesale so not sure who buys those from them and resells o try cheese of all nations on austin street in forest hills.
places like sullivan street bakery and amys may also offer a version of these, its worth a try and there are plenty of other fabulous breads and rolls to try like fennel raison at amy's and olive breads and twists.