Cutting onions for kebabs is fairly simple, the key is to cut them all about the same size. If the meat you will be using for the kebabs are cut into one inch cubes, you will want to cut all the onions roughly the same size. It really doesn't matter if your onions are layered one, two or three layers for the kebabs, we preferred two layers, some found three layers to be a little too much.
Trim off the stem and peel off the outer one or two layers of dry skin.
Cut the onion in half and halve them again, giving you four quarters.
Peel away the outer four layers from the inner core. Working with the outer four layers, separate each piece into two layers.
Cut each piece crosswise and trim if needed so that each is approximately the same size as the meat cubes you will be using for the kebabs.