Salty string cheese in brine
Try Highland Farms. Also not sure about the jar part, but they do sell an Armenian string cheese that I think did come from Montreal and it was massively salty. I had to soak it in water in order to eat it. It has nigella seeds in it. I have to say I like the Armenian string cheese in the US (Wegman's) much better because it is not so incredibly salty.
850 Ellesmere Rd, Toronto, ON M1P, CA