How to chop an onion

This is the easiest way to turn an onion into a bunch of little squares. The beauty of this is that the onion's ring structure does half the work for you. This is also a good time to sharpen your knife.

Whack both ends of the onion off and peel off the skin.

Slice in half length-wise and place face down on cutting board.
Hold the onion on both sides. Make length-wise cuts using the index finger of your holding hand to keep the previous slices from sliding out of formation. ( I need to take a picture of this clever little trick).

Pivot the onion 90 degrees and cut in the opposite direction. It will be hard to keep the already-cut pieces from falling out of form - but it doesn't matter since this is the last step.

When you get to the end, don't worry if you can't make a cut because there's nothing to hold onto. Unless your recipe calls for blood anyway, just cut the last little bit as best you can without holding it.

Obviously the widths of your cuts determines how course or fine your onions are.