Start with a beautiful, mold free onion.
Slice it in half, lengthwise.
Trim the ends.
Remove the peel, the first layer of tough onion and the core.
Put one of your onion halves flat-side down. At the ends that you already cut, begin cutting thin, EVEN slices.
Now, flip your onion around so that your slices are horizontal. Cut even slices. The same width as before.
Oops, I forgot to tell you that you should be holding the onion with one hand to keep your slices together.
Perfecto! Your skills amaze me.