Stopped in here for lunch the other day.
It's located in the lower level of the St Lawrence Market. It took a little time, but we found it.
The pierogies are tiny, but oh my goodness, they are delicious.
Also had a holubchi. Excellent.
I was disappointed that they didn't have kielbasa, but they directed me to another vendor on the same level. That's a different Yelp review........