When in need of 'real' Belgian fries you should ALWAYS buy them at a stall. When you get them in a little bag like this, you can be pretty sure they will be traditional ones. The ones on this picture definitely are! Mjam!!!
Haha, I don't think it's the bag that MAKES them authentic, yet it is often so that the authentic ones are IN such a bag. So if you want to be sure you've got good ones... You know :)