How do people make fried onions as an ingredient as opposed to a snack? Should I coat them with flour, milk, and spices?
You might want to look up recipes for &quot;Bawang Goreng&quot;, which are Indonesian fried shallots, which should also work for onions.  It's basically just thinly sliced shallots, deep fried until golden, and then drained.
You can buy containers of them at many international grocery stores.
If you're going to make them yourself, I would highly recommend purchasing a mandoline if you don't already have one.  This allows you to slice the onions very thinly (needed to make sure they dry out fully before they burn), and a consistent thickness (so they all cook in about the same time, and you don't have part of your batch burning before the rest are done).