Unique and DELICIOUS. This was actually the very first place I tried when I moved to Madison, and I immediately fell in love. They serve russian potato dumplings, which I had no idea existed until I came here. They're pretty much small potato dumplings (go figure) with tons of flavorful toppings, and you can dip them in sour cream (which I would highly recommend doing!).
It's fairly cheap and a half order of them is perfect for an afternoon snack. The place is somewhat small and kind of difficult to find, but it's quite a hidden gem right on the outskirts of State Street. I would definitely recommend getting a half order (or full order if you're hungry!) of the mix with the works. The mix is a mixture of beef and potato (you can choose to only have one or the other or both - I think the mix is by far the most enticing option), and the works is just all the delicious sauce they put on top, which includes cilantro and some spicy red sauce. I wouldn't worry if you're shy with spiciness, though - it's fairly mild.
Overall, I would HIGHLY recommend this place as it's a staple of downtown Madison and probably one of the most unique foods I've ever tried.