As mentioned above, Polish speakers often call mashed potatoes with farmer's cheese and onion Ruthenian pierogi (Polish: Ruskie pierogi),
that's what i think of when someone says ruskie (russian)
actually i beleive they are an invention from Ukraine
i checked wiki in PL and it said they most likely came from far east.. there was a mention of the Urals. hmm.. i know chinese have a very similar food item but the 'skin' is quite loose on them and i have never seen them filled with anything but ground beef.