And the answer is…. pickled bean sprouts.
This one threw me for a few days. It was one of the “no idea what it is, but I’ll give it a try” items, and the tight plastic casing with no air made me think it was some form of veggie-sausage. After several days delaying, I finally got up the nerve to give it a try and put it on the cutting board to cut off a slice – at which point it gushed brine all over the kitchen… cutting into a pressurized plastic tube is not recommended, I guess you are supposed to prick it with a pin first?
In any case good, if a touch salty.