Not in muy experience, I confess. One fries the onions until caramelised, then sautées the parboiled potato slices and, when crispy, one adds the onion back in. Parsley should be ubersprinkled prior to serving. This is how I grew up eating the dish and how I cook the dish. Indeed, I have eaten it in this form in Lyon. Perhaps there is a different version of which I know not?