In Canada, we always ate fries with white vinegar. It's difficult to find in restaurants so I always
had to ask the staff in other countries, to look under the sink with the cleaning supplies and just put out a small dish for me. (not under the sink, but on my table) In restaurants in the Caribbean, they eventually figured out that I would keep asking for vinegar, so they started to stock it. I recall one time when a waiter came to the table even before I had ordered, spanking new shaker of vinegar in his hand, big smile across his face.
It's still my favourite way to eat them.