How do you make "hot dogs with fried onions"? That sounds good.
Actually, quite simple. I just slice the onions thinly (take a half onion and instead of slicing in half circles, slice the other way to get strips). I just put them in a pan with some butter (or oil) and cook until they are just starting to caramelize and then I through the hot dogs in the same pan and cook until they are hot and brown on all sides. Keep stirring the onions.
Then I just load the bun with the hot dog and pile on the onions.